CVE-2026-3904
MediumCVSS 6.2Exploitation Probability (EPSS)
Low risk4th percentile - higher than 4% of all known CVEs
Summary
In the GNU C Library version 2.36 on x86_64 systems, calling functions that use nscd caching may cause a crash. The issue stems from an optimized memcmp implementation that, when inputs are concurrently modified by other threads, can crash the nscd client and the application using it.
Risk Assessment
This vulnerability can cause applications using nscd to crash under high load, leading to service disruption and potential denial of service.
Recommendation
Update the GNU C Library to a version containing the fix. Distributions that have cherry-picked the memcmp SSE2 optimization should also apply the patch to prevent nscd client crashes.
Other vulnerabilities in GNU C Library
See all- CVE-2026-0861High
Passing too large an alignment to the memalign suite of functions (memalign, posix_memalign, aligned_alloc) in GNU C Library versions 2.30 to 2.42 may result in an integer overflow, which could consequently result in heap corruption. To exploit this, an attacker must control both the size and alignment arguments; the size must be close to PTRDIFF_MAX and the alignment in the range [1<<62+1, 1<<63] (exactly 1<<63 for posix_memalign and aligned_alloc). In practice, alignment is typically not attacker-controlled, making exploitation unlikely.
- CVE-2024-2961High
The iconv() function in the GNU C Library versions 2.39 and older may overflow the output buffer by up to 4 bytes when converting strings to the ISO-2022-CN-EXT character set. This may lead to application crashes or overwrite a neighbouring variable.
- CVE-2025-0395Medium
In GNU C Library versions 2.13 to 2.40, when the assert() function fails, it does not allocate enough space for the assertion failure message string and size information, which may lead to a buffer overflow if the message string size aligns to page size.
- CVE-2025-4802Medium
In GNU C Library versions 2.27 to 2.38, an untrusted LD_LIBRARY_PATH environment variable vulnerability allows attacker-controlled loading of dynamically shared libraries in statically compiled setuid binaries that call dlopen (including internal dlopen calls after setlocale or calls to NSS functions).
- CVE-2026-5450Critical
Vulnerability in the GNU C Library (glibc) versions 2.7 through 2.43. Calling scanf family functions with %mc (malloc'd character match) and an explicit width greater than 1024 can cause a one-byte heap buffer overflow.
- CVE-2023-4911HighActively exploited
A buffer overflow was discovered in the GNU C Library's dynamic loader ld.so while processing the GLIBC_TUNABLES environment variable. This issue could allow a local attacker to use maliciously crafted GLIBC_TUNABLES environment variables when launching binaries with SUID permission to execute code with elevated privileges.
- CVE-2020-6096High
An exploitable signed comparison vulnerability exists in the ARMv7 memcpy() implementation of GNU glibc 2.30.9000. Calling memcpy() with a negative value for the 'num' parameter results in a signed comparison vulnerability, potentially leading to out-of-bounds memory writes and remote code execution.
- CVE-2018-19591High
In the GNU C Library (glibc) through version 2.28, attempting to resolve a crafted hostname via getaddrinfo() leads to the allocation of a socket descriptor that is not closed. This is related to the if_nametoindex() function.
- CVE-2026-84243High
A vulnerability in the GNU C Library (glibc) version 2.0 and later affects the gettext family of functions, which accept LANGUAGE environment variable entries containing '/' or equal to '..'. This allows an attacker to load a crafted message catalog (.mo file) from an arbitrary filesystem location, potentially crashing the program or executing arbitrary code with the program's privileges. The flaw is not covered by the earlier CVE-2014-0475 fix, which addressed other environment variables.
- CVE-2026-97399Low
The strncasecmp function in the GNU C Library 2.24 and later optimized for the Power8 architecture may read one byte beyond the input size limit, which may crash a program when that byte is not readable. This occurs when attacker-controlled input strings match up to the edge of their page and the neighboring page is either not mapped or not readable.
Original NVD description (English source)
Calling NSS-backed functions that support caching via nscd may call the nscd client side code and in the GNU C Library version 2.36 under high load on x86_64 systems, the client may call memcmp on inputs that are concurrently modified by other processes or threads and crash. The nscd client in the GNU C Library uses the memcmp function with inputs that may be concurrently modified by another thread, potentially resulting in spurious cache misses, which in itself is not a security issue. However in the GNU C Library version 2.36 an optimized implementation of memcmp was introduced for x86_64 which could crash when invoked with such undefined behaviour, turning this into a potential crash of the nscd client and the application that uses it. This implementation was backported to the 2.35 branch, making the nscd client in that branch vulnerable as well. Subsequently, the fix for this issue was backported to all vulnerable branches in the GNU C Library repository. It is advised that distributions that may have cherry-picked the memcpy SSE2 optimization in their copy of the GNU C Library, also apply the fix to avoid the potential crash in the nscd client.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

