What is CVE-2026-49838?

CVE-2026-49838 is a medium-severity vulnerability in Osrg Gobgp, classified under Improper Validation of Array Index. CVSS score: 5.9/10. Published 2026-09-10.

How severe is CVE-2026-49838?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Vulnerability in Osrg Gobgp

CVE-2026-49838

GoBGP is an open source Border Gateway Protocol (BGP) implementation in the Go Programming Language. Prior to version 4.7.0, GoBGP accepts a zero-length AS_PATH during UPDATE decoding and later panics while validating that attribute for a confederation eBGP peer. The vulnerable path is in the BGP UPDATE validator: a malformed UPDATE that should be rejected as a malformed AS_PATH instead reaches an unchecked `p.Value[0]` access, allowing a configured confederation eBGP peer to trigger a denial of service. Version 4.7.0 patches the issue.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Osrg Gobgp — versions < 4.7.0

Weakness classification (CWE)

CWE-129 — Improper Validation of Array Index

References

security-advisories@github.com (x_refsource_CONFIRM)
security-advisories@github.com (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-49838?: CVE-2026-49838 is a medium-severity vulnerability in Osrg Gobgp, classified under Improper Validation of Array Index. CVSS score: 5.9/10. Published 2026-09-10.
How severe is CVE-2026-49838?: Medium severity. CVSS v3 base score is 5.9 out of 10.