CVE-2026-49837
Description
GoBGP is an open source Border Gateway Protocol (BGP) implementation in the Go Programming Language. Versions prior to 4.6.0 contain a BGP OPEN capability parsing issue where several concrete capability decoders may parse data from the full remaining capability buffer instead of the slice bounded by the declared capability length, `CapLen`. A malformed BGP OPEN message can cause bytes from a following capability to be interpreted as part of the current capability. The most security-relevant case is the 4-octet AS capability, where a capability with `CapLen == 0` may cause the parser to read bytes from the following capability as the 4-octet AS value. This parsed value may later affect peer AS validation during BGP session establishment. Version 4.6.0 patches the issue.
How to fix
- github.com/osrg/gobgp/v44.6.0 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| github.com/osrg/gobgp/v4Go | v < 4.6.0 | 4.6.0 |
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