Medium severity · published Jun 18, 2026
CVE-2026-56099
OpenBSD mpls_do_error Kernel Stack Memory Disclosure via MPLS Input
5.3
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 43% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
SR
src · openbsd
before 6a23123ec05f1eb29cfcaae0f3a468b2e1983cfd · source: vendor
OP
Openbsd · Openbsd
before 2026-06-18 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-56099
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-56099
Patch
https://github.com/openbsd/src/commit/6a23123ec05f1eb29cfcaae0f3a468b2e1983cfd
Exploit
https://pop.argus-systems.ai/advisory/adv-040.html
Third Party Advisory
https://www.vulncheck.com/advisories/openbsd-mpls-do-error-kernel-stack-memory-disclosure-via-mpls-input
Exploit
http://seclists.org/fulldisclosure/2026/Jun/17
Exploit
http://www.openwall.com/lists/oss-security/2026/06/19/3