# CVE-2026-37462: GoBGP integer underflow in BGPUpdate.DecodeFromBytes

Source: https://junglewise.ai/threats/cve-2026-37462-gobgp-integer-underflow-in-bgpupdate-decodefrombytes  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-03. Updated: 2026-07-13  
License: CC BY 4.0 with a link back

CVE-2026-37462 · Severity: high · CVSS 7.3 · Published 2026-06-03

GoBGP is an open-source software implementation of the Border Gateway Protocol (BGP) used to manage internet routing. A vulnerability in how it processes routing updates allows a remote attacker to crash the service by sending a specially crafted message. This results in a denial of service, potentially disrupting network routing operations.

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-2026-37462 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-37462 being exploited in the wild.

**How severe is CVE-2026-37462?** High severity, with a CVSS score of 7.3, published 3 June 2026.

**Which products and versions are affected?** github.com/osrg/gobgp/v4 (Go) < 4.4.0, SEMVER:introduced=0,fixed=4.4.0; Osrg Gobgp < 4.4.0, 4.3.0.

**Is there a fix for CVE-2026-37462?** 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-2026-37462 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-37462?** 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

An integer underflow vulnerability exists in the BGPUpdate.DecodeFromBytes function within pkg/packet/bgp/bgp.go. When processing a malformed BGP UPDATE message that declares a section length smaller than the actual encoded element, the uint16 subtraction for 'routelen' or 'pathlen' wraps to a large value. This causes the decoding loop to consume data beyond the intended section boundary, leading to a crash or undefined behavior. The vulnerability can be triggered by a remote, unauthenticated attacker over the network. The issue is fixed in version 4.4.0 by adding bounds checks before subtraction.

## Affected products

- osrg GoBGP < 4.4.0

## Identifiers

- CVE-2026-37462
- GHSA-pw7p-7fqv-hpj8
- GO-2026-5971

## Timeline

- 2026-06-03: advisory: Initial disclosure and NVD publication
- 2026-07-13: patched: GitHub Advisory reviewed and patch confirmed in version 4.4.0

## References

- [https://github.com/osrg/gobgp/commit/9ce8936672ebc07df524da77fa4c6ae26d92be6d](https://github.com/osrg/gobgp/commit/9ce8936672ebc07df524da77fa4c6ae26d92be6d)
- [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)

## 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)
- [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)
- [GO-2026-5198 - GoBGP: Remote Denial of Service (Panic) via Malformed Well-known Path Attribute in github.com/osrg/gobgp](https://junglewise.ai/threats/cve-2026-41642-gobgp-has-remote-denial-of-service-panic-via-malformed-well-known)