Free Software Foundation glibc up to 2.44 Regular Expression Engine regex.c regcomp/regexec heap-based overflow

Summaryinfo

A vulnerability classified as critical has been found in Free Software Foundation glibc up to 2.44. This affects the function regcomp/regexec of the file regex.c of the component Regular Expression Engine. Performing a manipulation results in heap-based overflow. This vulnerability is identified as CVE-2026-100290. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability classified as critical has been found in Free Software Foundation glibc up to 2.44. This affects the function regcomp/regexec of the file regex.c of the component Regular Expression Engine. The manipulation with an unknown input leads to a heap-based overflow vulnerability. CWE is classifying the issue as CWE-122. The product writes past the end of a buffer that was allocated on the heap. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

The regcomp and regexec functions in the GNU C Library version 2.3 to version 2.44 may read freed memory and free the same heap block twice when a memory allocation fails while a regular expression is compiled or matched. The re_dfa_add_node (the NFA node table) and build_range_exp (bracket ranges) grow several arrays with consecutive realloc calls and store the new pointers only after all of them succeed. When a later call fails, the pattern buffer keeps pointers to blocks that were already freed, and the error cleanup frees them again. In regexec, the back-reference cache (match_ctx_add_entry) frees its array when a realloc fails but keeps the pointer, which is freed again on the error path. An attacker does not need to supply a crafted regular expression: patterns large enough to grow these arrays are common. The failure has to hit a specific allocation, though, so the issue can only be reached when the system is already under memory pressure. An attacker who supplies the pattern or the subject string has little control over which allocation fails, so the expected impact is a crash of the process. This issue affects all architectures and ABIs supported by the GNU C Library.

The advisory is shared at sourceware.org. This vulnerability is uniquely identified as CVE-2026-100290 since 09/25/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 11/11/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• Software Library

Vendor

• Free Software Foundation

Name

• glibc

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6
• 2.7
• 2.8
• 2.9
• 2.10
• 2.11
• 2.12
• 2.13
• 2.14
• 2.15
• 2.16
• 2.17
• 2.18
• 2.19
• 2.20
• 2.21
• 2.22
• 2.23
• 2.24
• 2.25
• 2.26
• 2.27
• 2.28
• 2.29
• 2.30
• 2.31
• 2.32
• 2.33
• 2.34
• 2.35
• 2.36
• 2.37
• 2.38
• 2.39
• 2.40
• 2.41
• 2.42
• 2.43
• 2.44

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

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Sourcesinfo

Entryinfo

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