# CVE-2026-37461: osrg GoBGP out-of-bounds read and underflow in BGP UPDATE parsing

Source: https://junglewise.ai/threats/cve-2026-37461-osrg-gobgp-out-of-bounds-read-and-underflow-in-bgp-update-parsing  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-04. Updated: 2026-05-11  
License: CC BY 4.0 with a link back

CVE-2026-37461 · Severity: high · CVSS 7.5 · Published 2026-05-04

GoBGP is an open-source implementation of the Border Gateway Protocol (BGP) used to manage how data is routed across the internet. A vulnerability in how it processes specific network update messages could allow an attacker to crash the service. This results in a denial-of-service (DoS) condition, potentially disrupting network routing and connectivity for organizations relying on this software.

Technologies: [github.com/osrg/gobgp/v4 (Go)](https://junglewise.ai/threats/technologies/github-com-osrg-gobgp-v4), [Osrg Gobgp](https://junglewise.ai/threats/technologies/gobgp). Vendors: [Go](https://junglewise.ai/threats/vendors/go), [Osrg](https://junglewise.ai/threats/vendors/osrg).

## Quick answers

**Is CVE-2026-37461 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-37461 being exploited in the wild.

**How severe is CVE-2026-37461?** High severity, with a CVSS score of 7.5, published 4 May 2026.

**Which products and versions are affected?** github.com/osrg/gobgp/v4 (Go) SEMVER:introduced=0,fixed=4.4.0.

**Is there a fix for CVE-2026-37461?** Yes. github.com/osrg/gobgp/v4 (Go): upgrade to 4.4.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-37461 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-37461?** Check whether you run github.com/osrg/gobgp/v4 (Go) or Osrg Gobgp at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/osrg/gobgp/v4 (Go): upgrade to 4.4.0 or later

  ```sh
  go get github.com/osrg/gobgp/v4@v4.4.0
  ```


## Technical details

Two related issues in GoBGP v4.3.0 contribute to potential instability. First, the 'ParseIP6Extended' function in 'bgp.go' performs an insufficient length check, validating only 8 bytes when 20 bytes are required for IPv6 extended community parsing, leading to an out-of-bounds read. Second, the 'DecodeFromBytes' function in 'BGPUpdate' is susceptible to a uint16 underflow when processing malformed UPDATE messages that declare section lengths smaller than the actual encoded elements. An unauthenticated remote attacker can exploit these flaws by sending specially crafted BGP UPDATE messages to trigger a crash (Denial of Service). Patches have been developed to enforce proper bounds checking and prevent integer wrapping.

## Affected products

- osrg GoBGP 4.3.0

## Identifiers

- CVE-2026-37461
- GHSA-wmvj-f67g-qg4g
- GO-2026-5713

## Timeline

- 2026-05-04: disclosed
- 2026-05-04: advisory

## References

- [https://github.com/osrg/gobgp/blob/v4.3.0/pkg/packet/bgp/bgp.go](https://github.com/osrg/gobgp/blob/v4.3.0/pkg/packet/bgp/bgp.go)
- [https://github.com/osrg/gobgp/commit/362cce3e325f56e7a4f792ccb9689b3bdda9e682](https://github.com/osrg/gobgp/commit/362cce3e325f56e7a4f792ccb9689b3bdda9e682)
- [https://github.com/osrg/gobgp/commit/9ce8936672ebc07df524da77fa4c6ae26d92be6d](https://github.com/osrg/gobgp/commit/9ce8936672ebc07df524da77fa4c6ae26d92be6d)

## Related threats

- [osrg GoBGP denial of service via empty AS_PATH attribute](https://junglewise.ai/threats/cve-2026-49838-osrg-gobgp-denial-of-service-via-empty-as-path-attribute)
- [GoBGP out-of-bounds read in BGP OPEN capability parser](https://junglewise.ai/threats/cve-2026-49837-gobgp-out-of-bounds-read-in-bgp-open-capability-parser)
- [GoBGP integer underflow in BGPUpdate.DecodeFromBytes](https://junglewise.ai/threats/cve-2026-37462-gobgp-integer-underflow-in-bgpupdate-decodefrombytes)
- [osrg GoBGP nil pointer dereference in AdjRib.Update](https://junglewise.ai/threats/cve-2026-42285-osrg-gobgp-nil-pointer-dereference-in-adjrib-update)
- [GoBGP has Remote Denial of Service (Panic) in UpdatePathAttrs4ByteAs via Malformed BGP UPDATE](https://junglewise.ai/threats/cve-2026-41643-gobgp-has-remote-denial-of-service-panic-in)