CVE-2026-56099

OpenBSD mpls_do_error Kernel Stack Memory Disclosure via MPLS Input

6.9 Medium

OpenBSD before commit 6a23123 (2026-06-18) contains an out-of-bounds read vulnerability in the mpls_do_error function within sys/netmpls/mpls_input.c that allows remote attackers to disclose kernel stack memory by sending crafted MPLS frames with 16 labels and no Bottom-of-Stack bit set.

Attack profile

How easy it is to exploit

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

What an attacker can affect

Confidentiality: Low
Integrity: None
Availability: None

Exploit likelihood

0.50%Up 0.1 points since Jun 23, 2026

What each source reports

CVE List Score used 6.9

OpenBSD mpls_do_error Kernel Stack Memory Disclosure via MPLS Input

Record: CVE-2026-56099
CVSS 4.0: 6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
CVSS 3.1: 5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Weakness: CWE-125
Updated: 2026-11-02

EUVDEUVD-2026-37938 6.9

Record: EUVD-2026-37938
CVSS 4.0: 6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
Updated: 2026-11-02

GitHub AdvisoriesGHSA-6qv5-f6m3-44g8 6.9

OpenBSD before commit 6a23123 (2026-06-18) contains an out-of-bounds read vulnerability in the...

Record: GHSA-6qv5-f6m3-44g8
CVSS 4.0: 6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1: 5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Weakness: CWE-125
Updated: 2026-11-02

NVD 6.9

Record: CVE-2026-56099
CVSS 4.0: 6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1: 5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CVSS 3.1: 5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Weakness: CWE-125
Updated: 2026-11-02

OSV 6.9

OpenBSD mpls_do_error Kernel Stack Memory Disclosure via MPLS Input

Record: CVE-2026-56099
CVSS 4.0: 6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
Weakness: CWE-125
Updated: 2026-11-02

Affected products

History

History
Recorded	Changed	Sources
Nov 2, 2026	aliases, products, published	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD, OSV

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

In short

CVE-2026-56099 is a medium vulnerability (CVSS 6.9) in Openbsd, published June 18, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.50%, the 43rd percentile. No source names a fixed version.