CVE-2025-43972 is a medium-severity (CVSS 6.8) CWE-1284 vulnerability in github.com/osrg/gobgp. A fix is available for github.com/osrg/gobgp — see the affected versions and patch details below.
GoBGP crashes in the flowspec parser
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-43972.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
github.com/osrg/gobgp🐹github.com/osrg/gobgp/v3Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
An issue was discovered in GoBGP before 3.35.0. An attacker can cause a crash in the pkg/packet/bgp/bgp.go flowspec parser by sending fewer than 20 bytes in a certain context.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/osrg/gobgp | all versions | No fix |
| 🐹Go | github.com/osrg/gobgp/v3 | all versions | 3.35.0go get github.com/osrg/gobgp/v3@v3.35.0 |
Affected Products
gobgposrgDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/osrg/gobgp, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
A fix is available for CVE-2025-43972; check the affected-versions list above or the advisory for the patched release of github.com/osrg/gobgp, then make sure no transitive dependency still pins the vulnerable range.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Frequently Asked Questions
Is CVE-2025-43972 in your dependencies?
Find it across Go, including transitive dependencies.