How severe is GHSA-fh2r-99q2-6mmg?

GHSA-fh2r-99q2-6mmg has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by GHSA-fh2r-99q2-6mmg?

GHSA-fh2r-99q2-6mmg affects the following packages: rustls-webpki (crates.io), rustls-webpki (crates.io). Ecosystems affected: crates.io.

How do I fix GHSA-fh2r-99q2-6mmg?

Update rustls-webpki to 0.100.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-fh2r-99q2-6mmg is resolved across your whole dependency graph.

How do I detect GHSA-fh2r-99q2-6mmg in my crates.io dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rustls-webpki. 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.

How do I mitigate GHSA-fh2r-99q2-6mmg if there is no patch (or I can't update yet)?

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 does O3 Security protect against GHSA-fh2r-99q2-6mmg?

O3 pinpoints whether GHSA-fh2r-99q2-6mmg is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-fh2r-99q2-6mmg actively exploited in the wild?

No public exploit code has been indexed for GHSA-fh2r-99q2-6mmg yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was GHSA-fh2r-99q2-6mmg published, and has it been updated?

GHSA-fh2r-99q2-6mmg was published on August 22, 2023 and was last updated on February 4, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🦀 crates.io

GHSA-fh2r-99q2-6mmg

HIGH

rustls-webpki: CPU denial of service in certificate path building

Also known asRUSTSEC-2023-0053

Published

Aug 22, 2023

Updated

Feb 4, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Blast Radius

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

When this crate is given a pathological certificate chain to validate, it will spend CPU time exponential with the number of candidate certificates at each step of path building.

Both TLS clients and TLS servers that accept client certificate are affected.

We now give each path building operation a budget of 100 signature verifications.

The original webpki crate is also affected, see GHSA-8qv2-5vq6-g2g7.

This was previously reported in the original crate https://github.com/briansmith/webpki/issues/69 and re-reported to us recently.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
🦀crates.io	`rustls-webpki`	all versions	0.100.2
🦀crates.io	`rustls-webpki`	≥ 0.101.0&&< 0.101.4	0.101.4

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rustls-webpki. 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 rustls-webpki to 0.100.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-fh2r-99q2-6mmg 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-fh2r-99q2-6mmg 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-fh2r-99q2-6mmg. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

When this crate is given a pathological certificate chain to validate, it will spend CPU time exponential with the number of candidate certificates at each step of path building. Both TLS clients and TLS servers that accept client certificate are affected. We now give each path building operation a budget of 100 signature verifications. The original `webpki` crate is also affected, see [GHSA-8qv2-5vq6-g2g7](https://github.com/advisories/GHSA-8qv2-5vq6-g2g7). This was previously reported in the original crate <https://github.com/briansmith/webpki/issues/69> and re-reported to us recently.

O3 Security · Impact-Aware SCA

Is GHSA-fh2r-99q2-6mmg in your dependencies?

O3 detects GHSA-fh2r-99q2-6mmg 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.

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