CVE-2026-107891

musl libc before 1.2.7, when an untrusted regular expression is used with regcomp, has multiple...

8.1 HighFix available

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.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: High
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: High
Integrity: High
Availability: High

Exploit likelihood

0.55%Scored on 2026-11-06. The trend appears after a second daily score.

What each source reports

CVE List Score used 8.1

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.

Record: CVE-2026-107891
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-190
Updated: 2026-11-05

EUVDEUVD-2026-117543 8.1

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.

Record: EUVD-2026-117543
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-05

GitHub AdvisoriesGHSA-mr8f-pr8h-27pc 8.1

musl libc before 1.2.7, when an untrusted regular expression is used with regcomp, has multiple...

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.

Record: GHSA-mr8f-pr8h-27pc
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-190
Updated: 2026-11-05

NVD 8.1

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.

Record: CVE-2026-107891
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-190
Updated: 2026-11-05

OSVALPINE-CVE-2026-107891 8.1

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.

Record: ALPINE-CVE-2026-107891
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-06

OSVBELL-CVE-2026-107891 8.1

Record: BELL-CVE-2026-107891
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-07

OSV 8.1

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.

Record: CVE-2026-107891
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-190
Updated: 2026-11-07

OSVDEBIAN-CVE-2026-107891 8.1

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.

Record: DEBIAN-CVE-2026-107891
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-06

OSVUBUNTU-CVE-2026-107891 8.1

[Unknown description]

Record: UBUNTU-CVE-2026-107891
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-07

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`musl` Alpine:v3.20	before 1.2.5-r4	1.2.5-r4
`musl` Alpine:v3.21	before 1.2.5-r12	1.2.5-r12
`musl` Alpine:v3.22	before 1.2.5-r13	1.2.5-r13
`musl` Alpine:v3.23	before 1.2.5-r24	1.2.5-r24
`musl` Alpine:v3.24	before 1.2.6-r3	1.2.6-r3
`musl-default` Alpaquita:23	1.2.3-r11 up to 1.2.4-r15	1.2.4-r15
`musl-perf` Alpaquita:23	1.2.3-r12 up to 1.2.4-r11	1.2.4-r11
`musl-default` Alpaquita:25	1.2.5-r12 up to 1.2.5-r17	1.2.5-r17
`musl-perf` Alpaquita:25	1.2.5-r11 up to 1.2.5-r19	1.2.5-r19
`musl-default` Alpaquita:stream	1.2.4-r0 up to 1.2.6-r6	1.2.6-r6

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Affected packages
Package	Affected	Fixed
`musl-perf` Alpaquita:stream	1.2.4-r1 up to 1.2.6-r6	1.2.6-r6
`musl-default` BellSoft Hardened Containers:23	1.2.3-r11 up to 1.2.4-r15	1.2.4-r15
`musl-perf` BellSoft Hardened Containers:23	1.2.3-r12 up to 1.2.4-r11	1.2.4-r11
`musl-default` BellSoft Hardened Containers:25	1.2.5-r12 up to 1.2.5-r17	1.2.5-r17
`musl-perf` BellSoft Hardened Containers:25	1.2.5-r11 up to 1.2.5-r19	1.2.5-r19
`musl-default` BellSoft Hardened Containers:stream	1.2.4-r0 up to 1.2.6-r6	1.2.6-r6
`musl-perf` BellSoft Hardened Containers:stream	1.2.4-r1 up to 1.2.6-r6	1.2.6-r6
`musl` Debian:12	All versions, plus listed versions 1.2.3-11.2.4-11.2.4-21.2.5-11.2.5-1.1 Show 6 moreShow less 1.2.5-21.2.5-31.2.5-3.11.2.5-3.1~deb13u11.2.6-11.2.6-2	None known
`musl` Debian:13	All versions, plus listed versions 1.2.5-31.2.5-3.11.2.5-3.1~deb13u11.2.6-11.2.6-2	None known
`musl` Debian:14	before 1.2.6-2, plus listed versions 1.2.5-31.2.5-3.11.2.5-3.1~deb13u11.2.6-1	1.2.6-2
`musl` Ubuntu:Pro:14.04:LTS	All versions, plus listed versions 0.9.14-20.9.14-2ubuntu10.9.15-10.9.15-1ubuntu0.1~esm10.9.15-1ubuntu0.1~esm2	None known
`musl` Ubuntu:Pro:16.04:LTS	All versions, plus listed versions 1.1.9-11.1.9-1ubuntu0.1~esm21.1.9-1ubuntu0.1~esm3	None known
`musl` Ubuntu:Pro:18.04:LTS	All versions, plus listed versions 1.1.16-31.1.18-11.1.19-11.1.19-1ubuntu0.1~esm1	None known
`musl` Ubuntu:Pro:20.04:LTS	All versions, plus listed versions 1.1.23-2build11.1.24-11.1.24-1ubuntu0.1~esm1	None known
`musl` Ubuntu:22.04:LTS	All versions, plus listed versions 1.2.2-11.2.2-4	None known
`musl` Ubuntu:24.04:LTS	All versions, plus listed versions 1.2.3-11.2.4-2	None known
`musl` Ubuntu:26.10	All versions, plus listed versions 1.2.5-3build11.2.6-1	None known
`musl` Ubuntu:26.04:LTS	All versions, plus listed versions 1.2.5-31.2.5-3build1	None known

History

History
Recorded	Changed	Sources
Nov 6, 2026	affected, aliases, references	OSV
Nov 5, 2026	published	OSV
Nov 5, 2026	references	EUVD, NVD, OSV
Nov 5, 2026	aliases, references, title	EUVD, GitHub Advisories
Nov 5, 2026	references	CVE List
Nov 5, 2026	aliases, cwes, description, products, references, severity	CVE List, EUVD
Nov 5, 2026	affected, facts	OSV
Nov 3, 2026	affected	OSV
Nov 2, 2026	first indexed	OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-107891 is a high vulnerability (CVSS 8.1) in Musl -libc Musl, published October 28, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.55%, the 46th percentile. Fixed in musl 1.2.5-r4.

References

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