GHSA-69x3-g4r3-p962
Blocklist Bypass possible via ECDSA Signature Malleability
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
github.com/slackhq/nebulaReal-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
Impact
When using P256 certificates (which is not the default configuration), it is possible to evade a blocklist entry created against the fingerprint of a certificate by using ECDSA Signature Malleability to use a copy of the certificate with a different fingerprint.
In order for this to affect a user or network, all of the following must be true:
CURVE_P256certificates are being used- There are one or more entries on the blocklist
- The certificates for those entries are signed by a trusted CA and not expired
- An attacker has a copy of the private key, and corresponding certificate, for one of those blocklist entries
Patches
See attached
Workarounds
If full copies of each certificate on the existing blocklist are available, it is possible to compute their opposite-chirality signature, and then the appropriate second fingerprint to list in the blocklist.
Rotating out all CAs that have signed hosts on the blocklist will also prevent exploitation of this vulnerability.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/slackhq/nebula | ≥ 1.7.0&&< 1.10.3 | 1.10.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/slackhq/nebula. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/slackhq/nebula to 1.10.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-69x3-g4r3-p962 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-69x3-g4r3-p962 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-69x3-g4r3-p962. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-69x3-g4r3-p962 in your dependencies?
O3 detects GHSA-69x3-g4r3-p962 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.