CVE-2026-19542

Calling tdelete on a sufficiently deep tree in the GNU C Library version 2.1 to 2.44 may write one pointer past the end of an alloca-allocated array on the stack, which may crash the application. The tdelete implementation keeps an explicit stack of parent nodes for rebalancing, which is grown as needed while descending the tree. Two rebalancing branches push an additional entry without checking the capacity, and write past the array when the stack is exactly full. Triggering this requires a node at a depth of exactly 40 (or 40 plus a multiple of 20), which implies a tree with at least a million nodes, so an attacker must drive a large number of insertions and deletions through an application that uses tsearch and tdelete. The written value is a pointer into a tree node and is not directly attacker controlled. No affected application in common distributions has been identified.

The GNU C Library project provides the core libraries for the GNU system and GNU/Linux systems, as well as many other systems that use Linux as the kernel. These libraries provide critical APIs including ISO C11, POSIX.1-2008, BSD, OS-specific APIs and more. These APIs include such foundational facilities as open, read, write, malloc, printf, getaddrinfo, dlopen, pthread_create, crypt, login, exit and more.

Security Fix(es):

CVE-2026-19542 is a vulnerability in the GNU C Library (glibc). Currently, no detailed description is available.(CVE-2026-19542)

A flaw was found in glibc. A remote attacker could exploit this vulnerability by providing specially crafted input during SHIFT_JISX0213 to UCS-4 text conversion. This crafted input can cause the application to repeatedly emit a buffered code point without consuming further input, leading to persistent retry churn. This can result in a denial of service (DoS) for callers converting untrusted text.(CVE-2026-77117)

A flaw was found in glibc. This vulnerability allows a remote attacker to cause a denial of service (DoS) by providing specially crafted text to an application that converts text from SHIFT_JISX0213 to UCS-4. The crafted input can lead to a continuous loop of processing, preventing the application from making progress and consuming resources. Exploitation requires specific conditions, including the application retrying conversion after an error with limited output space.(CVE-2026-80489)

The GNU C Library project provides the core libraries for the GNU system and GNU/Linux systems, as well as many other systems that use Linux as the kernel. These libraries provide critical APIs including ISO C11, POSIX.1-2008, BSD, OS-specific APIs and more. These APIs include such foundational facilities as open, read, write, malloc, printf, getaddrinfo, dlopen, pthread_create, crypt, login, exit and more.

Security Fix(es):

CVE-2026-19542 is a vulnerability in the GNU C Library (glibc). Currently, no detailed description is available.(CVE-2026-19542)

A flaw was found in glibc. A remote attacker could exploit this vulnerability by providing specially crafted input during SHIFT_JISX0213 to UCS-4 text conversion. This crafted input can cause the application to repeatedly emit a buffered code point without consuming further input, leading to persistent retry churn. This can result in a denial of service (DoS) for callers converting untrusted text.(CVE-2026-77117)

A flaw was found in glibc. This vulnerability allows a remote attacker to cause a denial of service (DoS) by providing specially crafted text to an application that converts text from SHIFT_JISX0213 to UCS-4. The crafted input can lead to a continuous loop of processing, preventing the application from making progress and consuming resources. Exploitation requires specific conditions, including the application retrying conversion after an error with limited output space.(CVE-2026-80489)

The glibc packages provide the standard C libraries (libc), POSIX thread libraries (libpthread), standard math libraries (libm), and the name service cache daemon (nscd) used by multiple programs on the system. Without these libraries, the Linux system cannot function correctly.

Security Fix(es):

• glibc: Process abort due to invalid memory in wordexp (CVE-2026-6368)

• glibc: Denial of Service via stack exhaustion during tilde expansion (CVE-2026-6791)

• glibc: Buffer Overflow in strfmon right-justification padding (CVE-2026-19499)

• glibc: Fix out-of-bounds array write in tdelete (CVE-2026-19542)

Bug Fix(es) and Enhancement(s):

• The iconv utility no longer returns exit status 1 after a successful //TRANSLIT transliteration

• A counter overflow in __wcsmbs_clone_conv that occurred when setlocale was called has been fixed

• A fcntl.h header conflict when compiling on Rocky Linux 10 has been resolved

• Minor documentation improvements have been picked up from upstream

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The glibc packages provide the standard C libraries (libc), POSIX thread libraries (libpthread), standard math libraries (libm), and the name service cache daemon (nscd) used by multiple programs on the system. Without these libraries, the Linux system cannot function correctly.

Security Fix(es):

• glibc: Glibc: Denial of Service via stack exhaustion during tilde expansion (CVE-2026-6791)

• glibc: glibc: Process abort due to invalid memory in wordexp (CVE-2026-6368)

• glibc: Fix out-of-bounds array write in tdelete (CVE-2026-19542)

• glibc: Non-progress DoS in SHIFT_JISX0213 -&gt (CVE-2026-77117)

• glibc: Non-progress DoS in SHIFT_JISX0213 -> UCS-4 conversion state (CVE-2026-80489)

• glibc: glibc: Heap buffer overflow via attacker-controlled fopen mode string (CVE-2026-18374)

Bug Fix(es) and Enhancement(s):

• glibc: Stop shipping glibc32-debuginfo package (in debug channels) [rhel-9] (JIRA:Rocky Linux-219516)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The glibc packages provide the standard C libraries (libc), POSIX thread libraries (libpthread), standard math libraries (libm), and the name service cache daemon (nscd) used by multiple programs on the system. Without these libraries, the Linux system cannot function correctly.

Security Fix(es):

• glibc: Fix out-of-bounds array write in tdelete (CVE-2026-19542)

• glibc: Non-progress DoS in SHIFT_JISX0213 -&gt (CVE-2026-77117)

• glibc: Non-progress DoS in EUC_JISX0213 -> UCS-4 conversion state (CVE-2026-80489)

• glibc: glibc: Heap buffer overflow via attacker-controlled fopen mode string (CVE-2026-18374)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Calling tdelete on a sufficiently deep tree in the GNU C Library version 2.1 to 2.44 may write one pointer past the end of an alloca-allocated array on the stack, which may crash the application. The tdelete implementation keeps an explicit stack of parent nodes for rebalancing, which is grown as needed while descending the tree. Two rebalancing branches push an additional entry without checking the capacity, and write past the array when the stack is exactly full. Triggering this requires a node at a depth of exactly 40 (or 40 plus a multiple of 20), which implies a tree with at least a million nodes, so an attacker must drive a large number of insertions and deletions through an application that uses tsearch and tdelete. The written value is a pointer into a tree node and is not directly attacker controlled. No affected application in common distributions has been identified.

The glibc packages provide the standard C libraries (libc), POSIX thread libraries (libpthread), standard math libraries (libm), and the name service cache daemon (nscd) used by multiple programs on the system. Without these libraries, the Linux system cannot function correctly.

Security Fix(es):

• glibc: Process abort due to invalid memory in wordexp (CVE-2026-6368)
• glibc: Denial of Service via stack exhaustion during tilde expansion (CVE-2026-6791)
• glibc: Buffer Overflow in strfmon right-justification padding (CVE-2026-19499)
• glibc: Fix out-of-bounds array write in tdelete (CVE-2026-19542)

Bug Fix(es) and Enhancement(s):

• The iconv utility no longer returns exit status 1 after a successful //TRANSLIT transliteration
• A counter overflow in __wcsmbs_clone_conv that occurred when setlocale was called has been fixed
• A fcntl.h header conflict when compiling on AlmaLinux 10 has been resolved
• Minor documentation improvements have been picked up from upstream

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The glibc packages provide the standard C libraries (libc), POSIX thread libraries (libpthread), standard math libraries (libm), and the name service cache daemon (nscd) used by multiple programs on the system. Without these libraries, the Linux system cannot function correctly.

Security Fix(es):

• glibc: Glibc: Denial of Service via stack exhaustion during tilde expansion (CVE-2026-6791)
• glibc: glibc: Process abort due to invalid memory in wordexp (CVE-2026-6368)
• glibc: Fix out-of-bounds array write in tdelete (CVE-2026-19542)
• glibc: Non-progress DoS in SHIFT_JISX0213 -&gt (CVE-2026-77117)
• glibc: Non-progress DoS in SHIFT_JISX0213 -> UCS-4 conversion state (CVE-2026-80489)
• glibc: glibc: Heap buffer overflow via attacker-controlled fopen mode string (CVE-2026-18374)

Bug Fix(es) and Enhancement(s):

• glibc: Stop shipping glibc32-debuginfo package (in debug channels) [almalinux-9] (JIRA:AlmaLinux-219516)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The glibc packages provide the standard C libraries (libc), POSIX thread libraries (libpthread), standard math libraries (libm), and the name service cache daemon (nscd) used by multiple programs on the system. Without these libraries, the Linux system cannot function correctly.

Security Fix(es):

• glibc: Fix out-of-bounds array write in tdelete (CVE-2026-19542)
• glibc: Non-progress DoS in SHIFT_JISX0213 -&gt (CVE-2026-77117)
• glibc: Non-progress DoS in EUC_JISX0213 -> UCS-4 conversion state (CVE-2026-80489)
• glibc: glibc: Heap buffer overflow via attacker-controlled fopen mode string (CVE-2026-18374)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Calling tdelete on a sufficiently deep tree in the GNU C Library version 2.1 to 2.44 may write one pointer past the end of an alloca-allocated array on the stack, which may crash the application.

The tdelete implementation keeps an explicit stack of parent nodes for rebalancing, which is grown as needed while descending the tree. Two rebalancing branches push an additional entry without checking the capacity, and write past the array when the stack is exactly full. Triggering this requires a node at a depth of exactly 40 (or 40 plus a multiple of 20), which implies a tree with at least a million nodes, so an attacker must drive a large number of insertions and deletions through an application that uses tsearch and tdelete. The written value is a pointer into a tree node and is not directly attacker controlled. No affected application in common distributions has been identified.

• CVE-2026-6368: posix: make wordexp work on a copy of we_wordv when WRDE_APPEND is set and restore the original on non-NOSPACE errors, preventing a use-after-free in wordfree; add tst-wordexp-append regression test
• CVE-2026-77117: iconvdata: clear the pending character in the SHIFT_JISX0213 decoder after emitting it, preventing an infinite conversion loop
• CVE-2026-19542: misc: use a fixed-size node stack with bounds asserts in tdelete to fix an out-of-bounds stack write during rebalancing

These are all security issues fixed in the glibc-2.44-2.1 package on the GA media of openSUSE Tumbleweed.

This update for glibc fixes the following issues:

• CVE-2026-6368: invalid free via wordexp WRDE_APPEND rollback (bsc#1274726).
• CVE-2026-6791: stack overflow in wordexp tilde expansion (bsc#1274723).
• CVE-2026-8674: reachable assert in resolv/resolv_conf.c:update_from_conf allows an attacker in a local network to trigger a process crash (bsc#1281297).
• CVE-2026-18374: heap buffer overflow in the fopen ccs extension (bsc#1277262).
• CVE-2026-19499: buffer overflow in strfmon right-justification padding (bsc#1276892).
• CVE-2026-19542: out-of-bounds array write in tdelete (bsc#1276946).
• CVE-2026-77117: SHIFT_JISX0213 decoding lacks pending character reset (bsc#1277921).
• CVE-2026-80489: EUC_JISX0213 decoding lacks pending character reset (bsc#1277922).
• CVE-2026-86805: TOCTOU race condition in the dynamic loader allows local attackers to escalate privileges (bsc#1282509).

Other changes:

• Add -flive-patching=inline-clone to avoid untraceable inter-procedural optimizations (bsc#1277247).

This update for glibc fixes the following issues:

• CVE-2026-6368: invalid free via wordexp WRDE_APPEND rollback (bsc#1274726).
• CVE-2026-6791: stack overflow in wordexp tilde expansion (bsc#1274723).
• CVE-2026-18374: heap buffer overflow in the fopen ccs extension (bsc#1277262).
• CVE-2026-19499: buffer overflow in strfmon right-justification padding (bsc#1276892).
• CVE-2026-19542: out-of-bounds array write in tdelete (bsc#1276946).
• CVE-2026-77117: SHIFT_JISX0213 decoding lacks pending character reset (bsc#1277921).
• CVE-2026-80489: EUC_JISX0213 decoding lacks pending character reset (bsc#1277922).

This update for glibc fixes the following issues:

• CVE-2026-6368: invalid free via wordexp WRDE_APPEND rollback (bsc#1274726).
• CVE-2026-6791: stack overflow in wordexp tilde expansion (bsc#1274723).
• CVE-2026-18374: heap buffer overflow in the fopen ccs extension (bsc#1277262).
• CVE-2026-19499: buffer overflow in strfmon right-justification padding (bsc#1276892).
• CVE-2026-19542: out-of-bounds array write in tdelete (bsc#1276946).
• CVE-2026-77117: SHIFT_JISX0213 decoding lacks pending character reset (bsc#1277921).
• CVE-2026-80489: EUC_JISX0213 decoding lacks pending character reset (bsc#1277922).

This update for glibc fixes the following issues:

• CVE-2026-6368: invalid free via wordexp WRDE_APPEND rollback (bsc#1274726).
• CVE-2026-6791: stack overflow in wordexp tilde expansion (bsc#1274723).
• CVE-2026-8674: reachable assert in resolv/resolv_conf.c:update_from_conf allows an attacker in a local network to trigger a process crash (bsc#1281297).
• CVE-2026-18374: heap buffer overflow in the fopen ccs extension (bsc#1277262).
• CVE-2026-19499: buffer overflow in strfmon right-justification padding (bsc#1276892).
• CVE-2026-19542: out-of-bounds array write in tdelete (bsc#1276946).
• CVE-2026-77117: SHIFT_JISX0213 decoding lacks pending character reset (bsc#1277921).
• CVE-2026-80489: EUC_JISX0213 decoding lacks pending character reset (bsc#1277922).
• CVE-2026-86805: TOCTOU race condition in the dynamic loader allows local attackers to escalate privileges (bsc#1282509).

Other changes:

• Add -flive-patching=inline-clone to avoid untraceable inter-procedural optimizations (bsc#1277247).

This update for glibc fixes the following issues:

• CVE-2026-6368: invalid free via wordexp WRDE_APPEND rollback (bsc#1274726).
• CVE-2026-6791: stack overflow in wordexp tilde expansion (bsc#1274723).
• CVE-2026-8674: reachable assert in resolv/resolv_conf.c:update_from_conf allows an attacker in a local network to trigger a process crash (bsc#1281297).
• CVE-2026-18374: heap buffer overflow in the fopen ccs extension (bsc#1277262).
• CVE-2026-19499: buffer overflow in strfmon right-justification padding (bsc#1276892).
• CVE-2026-19542: out-of-bounds array write in tdelete (bsc#1276946).
• CVE-2026-77117: SHIFT_JISX0213 decoding lacks pending character reset (bsc#1277921).
• CVE-2026-80489: EUC_JISX0213 decoding lacks pending character reset (bsc#1277922).
• CVE-2026-86805: TOCTOU race condition in the dynamic loader allows local attackers to escalate privileges (bsc#1282509).

Other changes:

• Add -flive-patching=inline-clone to avoid untraceable inter-procedural optimizations (bsc#1277247).

This update for glibc fixes the following issues:

• CVE-2026-6368: invalid free via wordexp WRDE_APPEND rollback (bsc#1274726).
• CVE-2026-6791: stack overflow in wordexp tilde expansion (bsc#1274723).
• CVE-2026-8674: reachable assert in resolv/resolv_conf.c:update_from_conf allows an attacker in a local network to trigger a process crash (bsc#1281297).
• CVE-2026-18374: heap buffer overflow in the fopen ccs extension (bsc#1277262).
• CVE-2026-19499: buffer overflow in strfmon right-justification padding (bsc#1276892).
• CVE-2026-19542: out-of-bounds array write in tdelete (bsc#1276946).
• CVE-2026-77117: SHIFT_JISX0213 decoding lacks pending character reset (bsc#1277921).
• CVE-2026-80489: EUC_JISX0213 decoding lacks pending character reset (bsc#1277922).
• CVE-2026-86805: TOCTOU race condition in the dynamic loader allows local attackers to escalate privileges (bsc#1282509).

Other changes:

• Add -flive-patching=inline-clone to avoid untraceable inter-procedural optimizations (bsc#1277247).

This update for glibc fixes the following issues:

• CVE-2026-6368: wordexp WRDE_APPEND rollback restores stale we_wordv, leading to invalid free in wordfree (bsc#1274726).
• CVE-2026-6791: wordexp: unbounded alloca (strndupa) in parse_tilde (bsc#1274723).
• CVE-2026-18374: overflow in the fopen ccs extension (bsc#1277262).
• CVE-2026-19542: Fix out-of-bounds array write in tdelete (bsc#1276946).
• CVE-2026-77117: non-progress DoS in SHIFT_JISX0213 -> UCS-4 conversion state handling (bsc#1277921).
• CVE-2026-80489: non-progress DoS in SHIFT_JISX0213 -> UCS-4 conversion state handling (bsc#1277922).

This update for glibc fixes the following issues:

• CVE-2026-6368: invalid free via wordexp WRDE_APPEND rollback (bsc#1274726).
• CVE-2026-6791: stack overflow in wordexp tilde expansion (bsc#1274723).
• CVE-2026-18374: heap buffer overflow in the fopen ccs extension (bsc#1277262).
• CVE-2026-19499: buffer overflow in strfmon right-justification padding (bsc#1276892).
• CVE-2026-19542: out-of-bounds array write in tdelete (bsc#1276946).
• CVE-2026-77117: SHIFT_JISX0213 decoding lacks pending character reset (bsc#1277921).
• CVE-2026-80489: EUC_JISX0213 decoding lacks pending character reset (bsc#1277922).

This update for glibc fixes the following issues:

• CVE-2026-6368: wordexp WRDE_APPEND rollback restores stale we_wordv, leading to invalid free in wordfree (bsc#1274726).
• CVE-2026-6791: wordexp: unbounded alloca (strndupa) in parse_tilde (bsc#1274723).
• CVE-2026-8674: reachable assert in resolv/resolv_conf.c:update_from_conf allows an attacker in a local network to trigger a process crash (bsc#1281297).
• CVE-2026-18374: overflow in the fopen ccs extension (bsc#1277262).
• CVE-2026-19542: Fix out-of-bounds array write in tdelete (bsc#1276946).
• CVE-2026-77117: non-progress DoS in SHIFT_JISX0213 -> UCS-4 conversion state handling (bsc#1277921).
• CVE-2026-80489: non-progress DoS in SHIFT_JISX0213 -> UCS-4 conversion state handling (bsc#1277922).
• CVE-2026-86805: TOCTOU race condition in the dynamic loader allows local attackers to escalate privileges (bsc#1282509).
• CVE-2026-89092: nscd stack overflow leads to degraded DNS resolution (bsc#1282449).
• CVE-2026-97399: one byte out-of-bounds read via function strncasecmp on Power8 can lead to a program crash (bsc#1283147).

It was discovered that GNU C Library had a buffer overflow in the strfmon function when handling right-justification padding. An attacker could possibly use this issue to cause a denial of service or execute arbitrary code. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-19499)

It was discovered that GNU C Library had an out-of-bounds stack array access in the tdelete function. An attacker could possibly use this issue to cause a denial of service or execute arbitrary code. (CVE-2026-19542)

It was discovered that GNU C Library incorrectly handled memory when calling wordexp with the WRDE_APPEND flag. An attacker could possibly use this issue to cause a denial of service. (CVE-2026-6368)

It was discovered that GNU C Library had a stack overflow in the wordexp function when expanding paths beginning with a tilde followed by a long username. An attacker could possibly use this issue to cause a denial of service or execute arbitrary code. (CVE-2026-6791)

It was discovered that GNU C Library had a hang in the SHIFT_JISX0213 character set converter. An attacker could possibly use this issue to cause a denial of service. (CVE-2026-77117)

It was discovered that GNU C Library had a hang in the EUC_JISX0213 character set converter. An attacker could possibly use this issue to cause a denial of service. (CVE-2026-80489)

USN-8737-1 fixed vulnerabilities in GNU C Library. This update provides the corresponding fixes for Ubuntu 24.04 LTS.

Original advisory details:

It was discovered that GNU C Library had a buffer overflow in the strfmon function when handling right-justification padding. An attacker could possibly use this issue to cause a denial of service or execute arbitrary code. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-19499)

It was discovered that GNU C Library had an out-of-bounds stack array access in the tdelete function. An attacker could possibly use this issue to cause a denial of service or execute arbitrary code. (CVE-2026-19542)

It was discovered that GNU C Library incorrectly handled memory when calling wordexp with the WRDE_APPEND flag. An attacker could possibly use this issue to cause a denial of service. (CVE-2026-6368)

It was discovered that GNU C Library had a stack overflow in the wordexp function when expanding paths beginning with a tilde followed by a long username. An attacker could possibly use this issue to cause a denial of service or execute arbitrary code. (CVE-2026-6791)

It was discovered that GNU C Library had a hang in the SHIFT_JISX0213 character set converter. An attacker could possibly use this issue to cause a denial of service. (CVE-2026-77117)

It was discovered that GNU C Library had a hang in the EUC_JISX0213 character set converter. An attacker could possibly use this issue to cause a denial of service. (CVE-2026-80489)