CVE-2026-26275 is a high-severity (CVSS 7.5) CWE-354 vulnerability in httpsig-hyper. A fix is available for httpsig-hyper — see the affected versions and patch details below.
httpsig-hyper has Improper Digest Verification that May Allow Message Integrity Bypass
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- 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 CVE-2026-26275.
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
CVE-2026-26275 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 377,333 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
httpsig-hyperReal-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
Impact
An issue was discovered in httpsig-hyper where Digest header verification could incorrectly succeed due to misuse of Rust's matches! macro. Specifically, the comparison:
if matches!(digest, _expected_digest)
treated _expected_digest as a pattern binding rather than a value comparison, resulting in unconditional success of the match expression.
As a consequence, digest verification could incorrectly return success even when the computed digest did not match the expected value.
Applications relying on Digest verification as part of HTTP message signature validation may therefore fail to detect message body modification. The severity depends on how the library is integrated and whether additional signature validation layers are enforced.
Patches
This issue has been fixed in:
httpsig-hyper>= 0.0.23
The fix replaces the incorrect matches! usage with proper value comparison and additionally introduces constant-time comparison for digest verification as defense-in-depth.
Regression tests have also been added to prevent reintroduction of this issue. Users are strongly advised to upgrade to the patched version.
Workarounds
There is no reliable workaround without upgrading. Users who cannot immediately upgrade should avoid relying solely on Digest verification for message integrity and ensure that full HTTP message signature verification is enforced at the application layer.
References
- PR: https://github.com/junkurihara/httpsig-rs/pull/14
- Follow-up hardening and test additions: https://github.com/junkurihara/httpsig-rs/pull/15
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | httpsig-hyper | all versions | 0.0.23cargo update -p httpsig-hyper --precise 0.0.23 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for httpsig-hyper, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update httpsig-hyper to 0.0.23 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-26275 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 CVE-2026-26275 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-26275. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-26275 in your dependencies?
O3 Security finds CVE-2026-26275 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.