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Not in CISA KEV
LOW severity

webpki: Name constraints for URI names were incorrectly acceptedGHSA-965h-392x-2mh5

LOW

GHSA-965h-392x-2mh5 is a low-severity (CVSS 2.2) CWE-295 vulnerability in rustls-webpki. A fix is available for rustls-webpki — see the affected versions and patch details below.

Also known asCVE-2026-93600RUSTSEC-2026-0098
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Nov 8, 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-965h-392x-2mh5.

EPSS Exploitation Probability

via FIRST.org ↗
0.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs10th percentile — riskier than 10% of all scored CVEsHighest risk
0.00%0.23%0.47%0.70%0.2%0.2%0.2%Oct 26Nov 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

2 pkgs affected
🦀rustls-webpki🦀rustls-webpki

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

rustls-webpki (rustls/webpki) versions 0.101.0 through 0.103.11 and 0.104.0-alpha releases before 0.104.0-alpha.6 ignore X.509 name constraints that apply to URI names, causing such constraints to be accepted rather than enforced. Because name constraints are restrictions on otherwise properly issued certificates, the flaw is only reachable after successful signature verification and requires a misissued certificate to exploit; the library also provides no API for asserting URI names, and URI name constraints are otherwise unimplemented. Versions 0.103.12 and 0.104.0-alpha.6 reject URI name constraints unconditionally.

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
🦀crates.iorustls-webpki≥ 0.101.0&&< 0.103.120.103.12cargo update -p rustls-webpki --precise 0.103.12
🦀crates.iorustls-webpki≥ 0.104.0-alpha.1&&< 0.104.0-alpha.60.104.0-alpha.6cargo update -p rustls-webpki --precise 0.104.0-alpha.6

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rustls-webpki, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update rustls-webpki to 0.103.12 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-965h-392x-2mh5 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

Name constraints for URI names were ignored and therefore accepted. Note this library does not provide an API for asserting URI names, and URI name constraints are otherwise not implemented. URI name constraints are now rejected unconditionally. Since name constraints are restrictions on otherwise properly-issued certificates, this bug is reachable only after signature verification and requires misissuance to exploit.
O3 Security · Impact-Aware SCA

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