CVE-2026-56099

MEDIUM

OpenBSD mpls_do_error Kernel Stack Memory Disclosure via MPLS Input

Title source: cna

Description

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.

References (3)

Core 3

Core References

Exploit technical-description exploit

https://pop.argus-systems.ai/advisory/adv-040.html

Patch patch

https://github.com/openbsd/src/commit/6a23123ec05f1eb29cfcaae0f3a468b2e1983cfd

View Patch ZIP pw:eip

Third Party Advisory third-party-advisory

https://www.vulncheck.com/advisories/openbsd-mpls-do-error-kernel-stack-memory-disclosure-via-mpls-input

Scores

CVSS v3 5.3

Attack Vector NETWORK

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Details

CWE

CWE-125

Status published

Products (1)

openbsd/src < 6a23123ec05f1eb29cfcaae0f3a468b2e1983cfd

Published Jun 18, 2026

Tracked Since Jun 19, 2026