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CVE-2026-49838: GoBGP confederation validation panics on empty AS_PATH attribute

• Severity: medium (CVSS 5.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-10 · updated 2026-09-16
• Weakness: CWE-129

Description

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.

Affected products

• osrg GoBGP: before 4.7.0

References

• https://github.com/osrg/gobgp/commit/4a319a6c25630fb3cdbda3e9ccfe56e702bdaaa0
• https://github.com/osrg/gobgp/security/advisories/GHSA-frrj-87jh-2772

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