musl libc regcomp overflows can cause heap writes (CVE-2026-107891)
Original title: CVE-2026-107891: musl libc: multiple integer overflow in regcomp, possibly leading to incorrect allocation sizes and out-of-bounds heap writes
Overflow conditions depend on the size and complexity of the regular expression passed to regcomp.
Rich Felker reported CVE-2026-107891 in musl libc. Multiple integer overflows in regcomp can produce incorrectly sized allocations and possibly out-of-bounds heap writes. The overflow conditions are triggered by the size and complexity of the regular expression passed to regcomp. The post does not state a fixed release or known exploitation.
Unconfirmed: Heap writes are described as possible, and no fixed version is stated.
- The affected function is regcomp in musl libc.
- Overflows can lead to incorrectly sized allocations.
- Out-of-bounds heap writes are described as possible.
- The remainder of the trigger description is cut off.
Impact: Possible out-of-bounds heap writes from regcomp
| Product | Affected |
|---|---|
| musl libc | — |
Vulnerabilities mentioned
All| CVE | Vulnerability | CVSS | EPSS | Signals | Published |
|---|---|---|---|---|---|
| CVE-2026-107891 | — | — | — |
From the original article
Posted by Rich Felker on Oct 21 CVE-2026-107891: musl libc: multiple integer overflow in regcomp, possibly leading to incorrect allocation sizes and out-of-bounds heap writes Overview: The regcomp function in musl libc is affected by multiple integer overflow issues which can lead to incorrectly-sized allocations and possibly out-of-bounds heap writes.
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