Vulnerabilidades do GNU C Library Glibc

CVE-2026-6238 Média · 6.5 CWE-126 28/04/2026

Buffer overread in ns_printrrf with corrupted RDATA field

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.

CVE-2026-5435 Alta · 7.3 CWE-787 28/04/2026

Potential buffer overflow in ns_sprintrrf TSIG handling path

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.

CVE-2026-5928 Alta · 7.5 CWE-127 20/04/2026

Potential buffer under-read in ungetwc

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.

CVE-2026-5450 Crítica · 9.8 CWE-787 20/04/2026

scanf %mc off-by-one heap buffer overflow

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.

CVE-2026-4046 Alta · 7.5 CWE-617 30/03/2026

iconv crash due to assertion failure with untrusted input

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.

CVE-2026-4438 Média · 5.4 CWE-20 20/03/2026

gethostbyaddr and gethostbyaddr_r return invalid DNS hostnames

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.

CVE-2026-4437 Alta · 7.5 CWE-125 20/03/2026

gethostbyaddr and gethostbyaddr_r may incorrectly handle DNS response

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.

CVE-2026-3904 Média · 6.2 CWE-366 11/03/2026

Calling NSS-backed functions that support caching via nscd may call the nscd client side…

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.

CVE-2025-15281 Alta · 7.5 CWE-908 20/01/2026

wordexp with WRDE_REUSE and WRDE_APPEND may return uninitialized memory

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.

CVE-2026-0915 Alta · 7.5 CWE-908 15/01/2026

getnetbyaddr and getnetbyaddr_r leak stack contents to DNS resovler

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.

CVE-2026-0861 Alta · 8.4 CWE-190 14/01/2026

Integer overflow in memalign leads to heap corruption

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.

CVE-2019-1010022 Crítica · 9.8 CWE-119 15/07/2019

GNU Libc current is affected by: Mitigation bypass. The impact is: Attacker may bypass stack...

GNU Libc current is affected by: Mitigation bypass. The impact is: Attacker may bypass stack guard protection. The component is: nptl. The attack vector is: Exploit stack buffer overflow vulnerability and use this bypass vulnerability to bypass stack guard. NOTE: Upstream comments indicate "this is being treated as a non-security bug and no real threat.