CVE-2026-6791

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):

Calling wordexp with WRDE_APPEND in the GNU C Library version 2.0 to version 2.43 can cause the interface to return invalid memory in the we_wordv member, which on subsequent calls to wordfree may abort the process.(CVE-2026-6368)

When expanding paths that begin with a tilde (~) followed by a username, the internal parse_tilde function extracts the username to determine the user's home directory. The implementation allocates memory for this username directly on the stack using the strndupa macro. Because the size of this allocation was determined by the length of the user-supplied input without any bounds checks, passing an excessively long username e.g. thousands of characters, forces the thread to exhaust its stack space. Thus if an application passes untrusted, attacker-controlled input to the wordexp function, an attacker can trigger a stack clash.(CVE-2026-6791)

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)

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: 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.

When expanding paths that begin with a tilde (~) followed by a username, the internal parse_tilde function extracts the username to determine the user's home directory. The implementation allocates memory for this username directly on the stack using the strndupa macro. Because the size of this allocation was determined by the length of the user-supplied input without any bounds checks, passing an excessively long username e.g. thousands of characters, forces the thread to exhaust its stack space. Thus if an application passes untrusted, attacker-controlled input to the wordexp function, an attacker can trigger a stack clash.

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)

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: 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.

When expanding paths that begin with a tilde (~) followed by a username, the internal parse_tilde function extracts the username to determine the user's home directory. The implementation allocates memory for this username directly on the stack using the strndupa macro. Because the size of this allocation was determined by the length of the user-supplied input without any bounds checks, passing an excessively long username e.g. thousands of characters, forces the thread to exhaust its stack space. Thus if an application passes untrusted, attacker-controlled input to the wordexp function, an attacker can trigger a stack clash.

Potential buffer overflow in ns_sprintrrf TSIG handling path. (CVE-2026-5435) Buffer overread in ns_printrrf with corrupted RDATA field. (CVE-2026-6238) wordexp with WRDE_APPEND can return or use invalid memory. (CVE-2026-6368) Potential stack-based buffer clash during tilde expansion in wordexp. (CVE-2026-6791) Fix right-justification in strfmon. (CVE-2026-19499) SHIFT_JISX0213 decoding lacks pending character reset. (CVE-2026-77117) EUC_JISX0213 decoding lacks pending character reset. (CVE-2026-80489)

These are all security issues fixed in the glibc-2.44-1.1 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)