How severe is CVE-2026-56099?

CVE-2026-56099 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2026-56099 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (34th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-56099?

CVE-2026-56099 affects Openbsd. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-56099?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-56099 have an EU (EUVD) identifier?

Yes. CVE-2026-56099 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-37938.

When was CVE-2026-56099 published?

CVE-2026-56099 was published on 2026-06-18 and last updated on 2026-06-27.

CVE-2026-56099

CVE-2026-56099 is a medium-severity vulnerability in Openbsd with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-125.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v4: 6.9
EPSS exploit prediction: 0% (34th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-37938
Weakness: CWE-125
Affected product: Openbsd
Published: 2026-06-18
Last modified: 2026-06-27

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.

Frequently asked questions

What is CVE-2026-56099?: 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.
How severe is CVE-2026-56099?: CVE-2026-56099 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2026-56099 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (34th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-56099?: CVE-2026-56099 affects Openbsd. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-56099?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-56099 have an EU (EUVD) identifier?: Yes. CVE-2026-56099 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-37938.
When was CVE-2026-56099 published?: CVE-2026-56099 was published on 2026-06-18 and last updated on 2026-06-27.

References

Affected products (1)

cpe:2.3:o:openbsd:openbsd:*:*:*:*:*:*:*:*

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