CVE-2026-49838 GoBGP confederation validation panics on empty AS_PATH attribute
A remote attacker with a configured confederation eBGP peer can cause a denial of service by sending a malformed BGP UPDATE with an empty AS_PATH.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-49838?
CVE-2026-49838 is a medium-severity vulnerability in osrg gobgp, published on 10 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-129
Which versions are affected by CVE-2026-49838?
3 open source packages ship an affected version, including github.com/osrg/gobgp/v4.
| Package | Affected | Fixed in |
|---|---|---|
github.com/osrg/gobgp/v4 Go | All versions | 4.7.0 |
github.com/osrg/gobgp/v4 Go | All versions | 4.7.0 |
github.com/osrg/gobgp/v4 Go | All versions | 4.7.0 |
How do I fix CVE-2026-49838?
Upgrade github.com/osrg/gobgp/v4 to 4.7.0 or later.
Is CVE-2026-49838 being exploited?
There is no known exploitation of CVE-2026-49838 in the wild and no public exploit code.
Sources
Also known as CLEANSTART-2026-HU02561, DEBIAN-CVE-2026-49838, GHSA-frrj-87jh-2772, GO-2026-5954, MINI-5wcc-p7h9-hf6p, MINI-7qjr-jr38-pfhc and 1 more.