GHSA-q7pg-9pr4-mrp2 is a medium-severity (CVSS 5.9) CWE-208 vulnerability in httpsig. A fix is available for httpsig — see the affected versions and patch details below.
httpsig-rs: HMAC verification is vulnerable to timing attack
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 GHSA-q7pg-9pr4-mrp2.
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.
How urgent is this, really
GHSA-q7pg-9pr4-mrp2 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
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 | 0.0.19cargo update -p httpsig --precise 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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-q7pg-9pr4-mrp2 can be triaged on real exposure rather than presence alone.
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 Security finds GHSA-q7pg-9pr4-mrp2 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.