GHSA-q7pg-9pr4-mrp2
MEDIUMhttpsig-rs: HMAC verification is vulnerable to timing attack
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
httpsigReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
Summary
HMAC signature comparison is not timing-safe and is vulnerable to timing attacks.
Details
SharedKey::sign() returns a Vec<u8> which has a non-constant-time equality implementation.
Hmac::finalize() returns a constant-time wrapper (CtOutput) which was discarded. Alternatively, Hmac has a constant-time verify() method.
The problem reported here is due to the following lines in SharedKey::sign() of the previous code:
let mut mac = HmacSha256::new_from_slice(key).unwrap();
mac.update(data);
Ok(mac.finalize().into_bytes().to_vec())
and the merged update changes the third line to directly verify with verify_slice.
Impact
Anyone who uses HS256 signature verification is vulnerably to Timing Attack that allows the attacker to forge a signature.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | httpsig | all versions | 0.0.19 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for httpsig. 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 httpsig to 0.0.19 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-q7pg-9pr4-mrp2 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-q7pg-9pr4-mrp2 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-q7pg-9pr4-mrp2. 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-q7pg-9pr4-mrp2 in your dependencies?
O3 detects GHSA-q7pg-9pr4-mrp2 across crates.io dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.