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CVE-2026-56099· NVD / CVE Program· CNA VulnCheck

OpenBSD mpls_do_error Kernel Stack Memory Disclosure via MPLS Input

Noroxi assessment

Priority: Monitor (action score 27/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.50% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: openbsd src 6a23123ec05f1eb29cfcaae0f3a468b2e1983cfd.

Low priority for now. Upgrade to openbsd src 6a23123ec05f1eb29cfcaae0f3a468b2e1983cfd or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 6.9 · v4.0—No exploit Fix available
Published
Jun 18, 2026
Updated
Jul 14, 2026
EPSS
0.5% · 41th percentile

Report tools

JSON

Action score

27

Monitor

Low priority for now.

CVSS
27 / 40 · 6.9 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · VulnCheck
6.9
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-56099

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
openbsdopenbsd

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • openbsd openbsdbefore 2026-06-18

Versions reported by the vendor

Affected version ranges reported by the assigning authority (VulnCheck). Independent of NVD's CPE analysis and usually ahead of it.

  • openbsd src

    • before 6a23123ec05f1eb29cfcaae0f3a468b2e1983cfdaffected · git

Same product

openbsd: all records

Other highest-scoring records for the same primary product.

  • CVE-2007-5365Stack-based buffer overflow in the cons_options function in options.c in dhcpd in OpenBSD 4.0 through 4.2, and some other dhcpd implementati
    52Plan
  • CVE-2007-1365Buffer overflow in kern/uipc_mbuf2.c in OpenBSD 3.9 and 4.0 allows remote attackers to execute arbitrary code via fragmented IPv6 packets du
    45Plan
  • CVE-2004-0220isakmpd in OpenBSD 3.4 and earlier allows remote attackers to cause a denial of service via an ISAKMP packet with a malformed Cert Request p
    41Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-41285Apr 20, 2026 · In OpenBSD through 7.8, the slaacd and rad daemons have an infinite loop when they receive a crafted ICMPv6 Neighbor Discovery (ND) option (
    17Monitor
  • ← EarlierCVE-2026-55706Jun 17, 2026 · sppp_pap_input in sys/net/if_spppsubr.c in OpenBSD before 076e2b1 allows authentication bypass via certain zero values for lengths.
    33Monitor
  • Later →CVE-2026-57589Jun 24, 2026 · sys/kern/sysv_sem.c in OpenBSD through 7.9 has a use-after-free allowing local privilege escalation to root.
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
openbsd src6a23123ec05f1eb29cfcaae0f3a468b2e1983cfdVendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
X

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

CVSS: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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records