CVE-2026-107891
Received Received - Intake

Heap Overflow in musl libc Due to Integer Overflow

Publication date: 2026-11-05

Last updated on: 2026-11-05

Assigner: MITRE

Description
musl libc before 1.2.7, when an untrusted regular expression is used with regcomp, has multiple integer overflows, possibly leading to incorrect allocation sizes and out-of-bounds heap writes.

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Meta Information

Published
2026-11-05
Last Modified
2026-11-05
Generated
2026-11-05
AI Q&A
2026-11-05
EPSS Evaluated
N/A
NVD
CVE-2026-107891
EUVD
EUVD-2026-117543

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
musl -libc musl 0.5.0

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-190 The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

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Executive Summary

CVE-2026-107891 is a vulnerability in musl libc before version 1.2.7 affecting the regcomp function. It involves multiple integer overflows that occur when processing untrusted regular expressions. These overflows can cause incorrect memory allocation sizes and lead to out-of-bounds heap writes.

Detection Guidance

To detect this vulnerability, check the version of musl libc on your system. Run 'musl-gcc --version' or check the libc version via 'ldd --version'. If the version is 1.2.6 or earlier, the system is vulnerable. Additionally, monitor applications that process untrusted regular expressions for crashes or heap corruption.

Impact Analysis

This vulnerability can cause denial-of-service through crashes or, in some cases, allow arbitrary code execution depending on heap usage and concurrent execution. It only affects applications that process regular expressions from untrusted sources using the regcomp function.

Mitigation Strategies

Immediately upgrade musl libc to version 1.2.7 or later. If upgrading is not possible, avoid processing regular expressions from untrusted sources in your applications. Apply any vendor-provided patches for affected systems.

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