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Fencer Vulns
high 7.5

CVE-2026-41643 json

GoBGP: Remote Denial of Service (Panic) in UpdatePathAttrs4ByteAs via Malformed BGP UPDATE

published 2026-04-29 6 mo ago modified 2026-10-26 13 d ago also GHSA-8rxh-r2p6-7f2q , GO-2026-5266 , EUVD-2026-28352

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 45%
public exploits
0
none known

Summary

GoBGP is an open source Border Gateway Protocol (BGP) implementation in the Go Programming Language. Prior to version 4.3.0, a remote Denial of Service (DoS) vulnerability exists in GoBGP where a malformed BGP UPDATE message can trigger a runtime error: index out of range panic. This occurs during the processing of 4-byte AS attributes when the message structure causes an internal slice index shift that is not properly handled. This issue has been patched in version 4.3.0.

Patch / fix

  • go github.com/osrg/gobgp/v4 4.3.0
  • osrg gobgp 4.3.0
  • gobgp Debian 14 4.3.0-1

debian advisories DEBIAN-CVE-2026-41643

  • gobgp Ubuntu Pro 18.04 LTS 1.29-1ubuntu0.1+esm2
  • gobgp Ubuntu Pro 20.04 LTS 2.12.0-1ubuntu0.1~esm3
  • gobgp Ubuntu Pro 22.04 LTS 2.25.0-3ubuntu0.1+esm4
  • gobgp Ubuntu Pro 24.04 LTS 3.23.0-1ubuntu0.3+esm4
  • gobgp Ubuntu Pro 26.04 LTS 3.36.0-2ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2026-41643

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • govulncheck-vulndb SLES 16.0, SLES for SAP applications 16.0 0.0.20260727T201416-160000.1.1

suse advisories SUSE-SU-2026:23216-1SUSE-SU-2026:23227-1

  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260727T201416-160000.1.1

opensuse advisories openSUSE-SU-2026:21551-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-41643 updated cvss 7.5

github.com/osrg/gobgp: GoBGP: Denial of Service via malformed BGP UPDATE message

  • Red Hat OpenShift Container Platform 4 openshift4/metallb-rhel8
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
6 mo ago

Exploit prediction

0.54% chance of exploitation in the next 30 days, higher than 45% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/osrg/gobgp/security/advisories/GHSA-8rxh-r2p6-7f2q referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
go github.com/osrg/gobgp/v4
<4.3.0
4.3.0

Affected products

  • osrg gobgp

Classification

Weakness
  • CWE-129 Improper Validation of Array Index

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.