CVE-2026-19499

Calling strfmon and strfmon_l in the GNU C Library version 2.38 to 2.44 can write past the end of the caller-supplied output buffer when a conversion uses right-justified width padding. Exploitation requires an application code path that calls strfmon or strfmon_l with right-justified width padding into a destination buffer that is large enough for the padding to succeed but too small for the internal memmove call. The field width or format may be attacker-influenced or a fixed susceptible pattern in the caller. At the time of publication, no network-facing application impact is known.

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):

A flaw was found in glibc. The strfmon and strfmon_l functions are vulnerable to a buffer overflow when processing right-justified width padding. This occurs because an incorrect length is used for an internal memory operation, causing data to be written beyond its intended buffer. An attacker could exploit this by providing specially crafted input, potentially leading to arbitrary code execution or other severe impacts.(CVE-2026-19499)

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):

A flaw was found in glibc. The strfmon and strfmon_l functions are vulnerable to a buffer overflow when processing right-justified width padding. This occurs because an incorrect length is used for an internal memory operation, causing data to be written beyond its intended buffer. An attacker could exploit this by providing specially crafted input, potentially leading to arbitrary code execution or other severe impacts.(CVE-2026-19499)

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):

Passing an effectively empty string to the ,ccs= syntax extension of the mode argument in the fopen function in the GNU C Library version 2.45 or earlier may result in a heap buffer overflow when the mode string input to the function is attacker controlled. This usage pattern is not seen in applications in common GNU/Linux distributions and applications that process user-supplied values for ccs should not pass them through without validation.(CVE-2026-18374)

A flaw was found in glibc. The strfmon and strfmon_l functions are vulnerable to a buffer overflow when processing right-justified width padding. This occurs because an incorrect length is used for an internal memory operation, causing data to be written beyond its intended buffer. An attacker could exploit this by providing specially crafted input, potentially leading to arbitrary code execution or other severe impacts.(CVE-2026-19499)

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.

Calling strfmon and strfmon_l in the GNU C Library version 2.38 to 2.44 can write past the end of the caller-supplied output buffer when a conversion uses right-justified width padding. Exploitation requires an application code path that calls strfmon or strfmon_l with right-justified width padding into a destination buffer that is large enough for the padding to succeed but too small for the internal memmove call. The field width or format may be attacker-influenced or a fixed susceptible pattern in the caller. At the time of publication, no network-facing application impact is known.

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.

Calling strfmon and strfmon_l in the GNU C Library version 2.38 to 2.44 can write past the end of the caller-supplied output buffer when a conversion uses right-justified width padding.

Exploitation requires an application code path that calls strfmon or strfmon_l with right-justified width padding into a destination buffer that is large enough for the padding to succeed but too small for the internal memmove call. The field width or format may be attacker-influenced or a fixed susceptible pattern in the caller.

At the time of publication, no network-facing application impact is known.

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-2.44-2.1 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).

Root has patched CVE-2026-19499 in the glibc package for Root:Debian:12. Multiple fixed versions available.

Root has patched CVE-2026-19499 in the glibc package for Root:Debian:13. Multiple fixed versions available.

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: 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).

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)