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 condition may happen when the input strings to the strncasecmp function are attacker controlled in an application and they match all the way up to the edge of their page and the neighbouring page is either not mapped or is not readable.
CVE-2026-95818 is a stack-based buffer overflow vulnerability in the dynamic loader (ld.so) of the GNU C Library (glibc) versions 2.14 through 2.44. This flaw affects setuid/setgid programs that use DT_RPATH or DT_RUNPATH beginning with $ORIGIN followed by a NUL or '/' character. Exploitation can cause the loader to read and write beyond the bounds of internal buffers, leading to crashes or limited disclosure of process memory. The vulnerability has a low CVSS score of 3.6 and requires local attacker privileges with high attack complexity.
A time-of-check to time-of-use (TOCTOU) race condition in the dynamic loader (ld.so) of the GNU C Library (glibc) versions 2.14 through 2.44 allows a local attacker to escalate privileges. When expanding $ORIGIN in DT_RPATH for setuid/setgid (AT_SECURE) programs, glibc validates the lexically normalized search path against the trusted directories but then opens the raw, un-normalized path. On systems where the Linux fs.protected_hardlinks sysctl is disabled, a local attacker who hard-links such a program into an attacker-controlled directory and wins a race to replace an intermediate path component with a symbolic link can direct the loader outside the trusted directory, causing it to load an attacker-controlled shared object and execute arbitrary code with the elevated privileges of the program.
Exploitation requires an installed setuid or setgid binary whose DT_RPATH uses $ORIGIN followed by ".." traversal that normalizes into a trusted directory, and the ability to hard-link that binary and win the race by swapping a path component for a symbolic link. Major Linux-based OS distributions ship with fs.protected_hardlinks enabled by default and mitigate the vulnerability.
CVE-2026-8674 is a reachable assertion vulnerability in the GNU C Library (glibc) affecting versions 2.26 through 2.44. It occurs when the DNS stub resolver initializes from an /etc/resolv.conf file or LOCALDOMAIN environment variable with a search list containing a domain roughly 200 characters or longer. This triggers an assertion failure that aborts the process. The flaw arises because the resolver truncates the search list into a fixed-size buffer but performs a consistency check against the wrong size, causing a valid truncated list to fail the assertion. Any process performing name resolution via glibc is affected, including long-running processes that reload /etc/resolv.conf after changes. Attackers on the local network may trigger this without privileges, leveraging DHCP or VPN server configurations that update search domains.
CVE-2026-80489 is a medium severity vulnerability in the GNU C Library (glibc) versions 2.3 through 2.44. It involves an infinite loop condition when converting crafted EUC_JISX0213 input to UCS-4 or the internal wide character encoding, such as via iconv. The flaw occurs because the converter improperly handles certain two-code-point sequences when the output buffer is too small, causing the application to hang indefinitely. This affects only the EUC_JISX0213 character set, which is uncommon.
The nscd service in the GNU C Library 2.3.4 onwards may crash due to a
stack overflow when a malicious DNS server returns too large a response
for a DNS query, resulting in degraded DNS resolution for the system.
Exploitation of this bug needs a system that has nscd enabled and using
an untrusted DNS server for name resolution, with the compromised DNS
server being capable of processing records large enough to result in a
stack overflow in an nscd thread stack. During experimentation, bind 9
was unable to handle large records, but that could change in future or
with a different name server. In typical installations, nscd is
executed in an isolated context as its own user without a shell, due to
which any compromise of that service is isolated.
There is a remote possibility of nscd cache corruption if an attacker
manages to get the stack pointer into a desired point in the heap,
potentially resulting in other caches in nscd being overwritten with
corrupt data through the stack overflow, until the buggy code path
eventually results in a crash.
Finally, a crash in nscd may result in performance degradation when
resolving names, but it does not result in a denial of service.
CVE-2026-18374 is a medium severity buffer overflow vulnerability in the GNU C Library (glibc) affecting version 2.45 and earlier. It occurs when an attacker-controlled mode string passed to the fopen function uses the ,ccs= syntax extension with an effectively empty string, potentially causing a heap buffer overflow. This usage pattern is uncommon in typical GNU/Linux applications, and applications should validate user-supplied ccs values before passing them to fopen.
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 deprecated functions ns_printrrf, ns_printrr and fp_nquery in the GNU C Library version 2.0.1 to version 2.43 fail to validate the RDATA content against the RDATA length in a DNS response when processing A6, CERT, LOC, TKEY or TSIG records, which may allow an attacker to craft a DNS response, causing a target application to crash or read uninitialized memory.
These functions are for application debugging only and hence not in the path of code executed by the DNS resolver. Further, they have been deprecated since version 2.34 and should not be used by any new applications. Applications should consider porting away from these interfaces since they may be removed in future versions.
The deprecated functions ns_printrrf, ns_printrr and fp_nquery in the GNU C Library version 2.2 and newer fail to enforce the caller-supplied buffer length, and can result in an out-of-bounds write when printing TSIG records.
Calling the scanf family of functions with a %mc (malloc'd character match) in the GNU C Library version 2.7 to version 2.43 with a format width specifier with an explicit width greater than 1024 could result in a one byte heap buffer overflow.
Calling the ungetwc function on a FILE stream with wide characters encoded in a character set that has overlaps between its single byte and multi-byte character encodings, in the GNU C Library version 2.43 or earlier, may result in an attempt to read bytes before an allocated buffer, potentially resulting in unintentional disclosure of neighboring data in the heap, or a program crash.
A bug in the wide character pushback implementation (_IO_wdefault_pbackfail in libio/wgenops.c) causes ungetwc() to operate on the regular character buffer (fp->_IO_read_ptr) instead of the actual wide-stream read pointer (fp->_wide_data->_IO_read_ptr). The program crash may happen in cases where fp->_IO_read_ptr is not initialized and hence points to NULL. The buffer under-read requires a special situation where the input character encoding is such that there are overlaps between single byte representations and multibyte representations in that encoding, resulting in spurious matches. The spurious match case is not possible in the standard Unicode character sets.
The iconv() function in the GNU C Library versions 2.43 and earlier may crash due to an assertion failure when converting inputs from the IBM1390 or IBM1399 character sets, which may be used to remotely crash an application.
This vulnerability can be trivially mitigated by removing the IBM1390 and IBM1399 character sets from systems that do not need them.
Calling gethostbyaddr or gethostbyaddr_r with a configured nsswitch.conf that specifies the library's DNS backend in the GNU C library version 2.34 to version 2.43 could result in an invalid DNS hostname being returned to the caller in violation of the DNS specification.
Calling gethostbyaddr or gethostbyaddr_r with a configured nsswitch.conf that specifies the library's DNS backend in the GNU C Library version 2.34 to version 2.43 could, with a crafted response from the configured DNS server, result in a violation of the DNS specification that causes the application to treat a non-answer section of the DNS response as a valid answer.
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.
Calling wordexp with WRDE_REUSE in conjunction with WRDE_APPEND in the GNU C Library version 2.0 to version 2.42 may cause the interface to return uninitialized memory in the we_wordv member, which on subsequent calls to wordfree may abort the process.
Calling getnetbyaddr or getnetbyaddr_r with a configured nsswitch.conf that specifies the library's DNS backend for networks and queries for a zero-valued network in the GNU C Library version 2.0 to version 2.42 can leak stack contents to the configured DNS resolver.
Passing too large an alignment to the memalign suite of functions (memalign, posix_memalign, aligned_alloc) in the GNU C Library version 2.30 to 2.42 may result in an integer overflow, which could consequently result in a heap corruption.
Note that the attacker must have control over both, the size as well as the alignment arguments of the memalign function to be able to exploit this. The size parameter must be close enough to PTRDIFF_MAX so as to overflow size_t along with the large alignment argument. This limits the malicious inputs for the alignment for memalign to the range [1<<62+ 1, 1<<63] and exactly 1<<63 for posix_memalign and aligned_alloc.
Typically the alignment argument passed to such functions is a known constrained quantity (e.g.page size, block size, struct sizes) and is not attacker controlled, because of which this may not be easily exploitable in practice. An application bug could potentially result in the input alignment being too large, e.g.due to a different buffer overflow or integer overflow in the application or its dependent libraries, but that is again an uncommon usage pattern given typical sources of alignments.
The regcomp function in the GNU C library version from 2.4 to 2.41 is
subject to a double free if some previous allocation fails. It can be
accomplished either by a malloc failure or by using an interposed malloc
that injects random malloc failures. The double free can allow buffer
manipulation depending of how the regex is constructed. This issue
affects all architectures and ABIs supported by the GNU C library.
