What is CVE-2026-107891?

CVE-2026-107891 is a high-severity vulnerability in Musl -Libc, classified under Integer Overflow or Wraparound. CVSS score: 8.1/10. Published 2026-11-05.

How severe is CVE-2026-107891?

High severity. CVSS v3 base score is 8.1 out of 10.

Integer overflow in Musl -Libc

CVE-2026-107891

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.

Vulnerability class: Integer Overflow

Published 2026-11-05 · last modified 2026-11-05.

CVSS v3 metric

CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.005 (46.2th percentile), scored 2026-11-09.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 46th percentile — 46.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

The 30-day trend appears once there are two daily scores.

Affected products

Musl -Libc

Weakness classification (CWE)

CWE-190 — Integer Overflow or Wraparound

References

Frequently asked questions

What is CVE-2026-107891?: CVE-2026-107891 is a high-severity vulnerability in Musl -Libc, classified under Integer Overflow or Wraparound. CVSS score: 8.1/10. Published 2026-11-05.
How severe is CVE-2026-107891?: High severity. CVSS v3 base score is 8.1 out of 10.