GHSA-g9mp-8g3h-3c5c
Fix: flynn/noise#44GHSA-g9mp-8g3h-3c5c is a CWE-311 vulnerability in github.com/flynn/noise. O3 Security confirms whether GHSA-g9mp-8g3h-3c5c is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
flynn/noise has improper nonce handling yielding potential state DoS
Real-World Exposure
github.com/flynn/noiseReal-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
The Go package github.com/flynn/noise, a Noise Protocol implementation, has two bugs in nonce handling in versions prior to v1.0.0.
Issue 1: Potential nonce overflow
If 2<sup>64</sup> (~18.4 quintillion) or more messages are encrypted with Encrypt after handshaking, the nonce counter will wrap around, causing multiple messages to be encrypted with the same key and nonce, resulting in a potentially catastrophic weakening of the security properties of the symmetric cipher.
This has been resolved in the patched version by returning ErrMaxNonce from the CipherState Encrypt and Decrypt methods before the reserved maximum nonce is reached. If this error is encountered, the program should handshake again to start with a fresh CipherState.
Issue 2: Potential denial of service via invalid ciphertext
If an attacker sends an invalid ciphertext into one peer's Decrypt, the nonce is incremented unconditionally. This causes a desync of the CipherState due to a nonce mismatch between the peers, resulting in a failure to decrypt all subsequent messages. A new handshake will be required to establish a new CipherState.
This has been resolved in the patched version by returning authentication errors from Decrypt before incrementing the nonce.
Patches
Fixed in https://github.com/flynn/noise/pull/44, tagged as v1.0.0.
Acknowledgements
These issues were discovered during an audit of a user of this package (dnstt). Thanks to UC Berkley for commissioning the audit, and to David Fifield and Nathan Brown for their collaboration on the fixes. The fixed issues are noted in the audit as:
- UCB-02-003 Potential nonce overflow in Noise protocol
- UCB-02-006 DoS due to unconditional nonce increment
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/flynn/noise | all versions | 1.0.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/flynn/noise. 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/flynn/noise to 1.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g9mp-8g3h-3c5c 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-g9mp-8g3h-3c5c 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-g9mp-8g3h-3c5c. 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-g9mp-8g3h-3c5c in your dependencies?
O3 detects GHSA-g9mp-8g3h-3c5c across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.