CVE-2026-56099 OpenBSD mpls_do_error Kernel Stack Memory Disclosure via MPLS Input

Medium 6.9 Published 18 Jun 2026 Updated 14 Jul 2026

Remote attackers can disclose kernel stack memory by sending crafted MPLS frames to OpenBSD systems, potentially exposing sensitive data.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-56099?

CVE-2026-56099 is a medium-severity vulnerability in Openbsd Openbsd, published on 18 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-125

Which versions are affected by CVE-2026-56099?

It affects 1 product.

Products include Openbsd Openbsd.

How do I fix CVE-2026-56099?

No fix has been published for CVE-2026-56099 yet. Limit exposure of the affected software until one is available.

Is CVE-2026-56099 being exploited?

There is no known exploitation of CVE-2026-56099 in the wild and no public exploit code.

All Openbsd Openbsd vulnerabilities

Sources

Also known as GHSA-6qv5-f6m3-44g8.