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MEDIUM severity

httpsig-rs: HMAC verification is vulnerable to timing attackGHSA-q7pg-9pr4-mrp2

MEDIUMFix: junkurihara/httpsig-rs@fc095b6

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.

Also known asCVE-2025-59058
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

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

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs21th percentile — riskier than 21% of all scored CVEsHighest risk
0.00%0.26%0.52%0.78%0.0%0.3%May 26Aug 26Nov 26

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

1 pkg affected
🦀httpsig

Real-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

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🦀crates.iohttpsigall versions0.0.19cargo update -p httpsig --precise 0.0.19

Detection & mitigation playbook

Open-source dependency

  1. Detect

    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.

  2. 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.

  3. 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.

Frequently Asked Questions

### 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`](https://docs.rs/digest/0.10.7/digest/struct.CtOutput.html)) 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: ```rust let mut mac = HmacSha256::new_from_slice(key).unwrap(); mac.update(data); Ok(mac
O3 Security · Impact-Aware SCA

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httpsig-rs: HMAC verification is vulnerable to timing attack