How severe is GHSA-7m29-f4hw-g2vx?

No CVSS score has been assigned to GHSA-7m29-f4hw-g2vx yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-7m29-f4hw-g2vx?

GHSA-7m29-f4hw-g2vx affects the following packages: github.com/refraction-networking/utls (Go). Ecosystems affected: Go.

How do I fix GHSA-7m29-f4hw-g2vx?

Update github.com/refraction-networking/utls to 1.8.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-7m29-f4hw-g2vx is resolved across your whole dependency graph.

How do I detect GHSA-7m29-f4hw-g2vx in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/refraction-networking/utls. 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-7m29-f4hw-g2vx 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-7m29-f4hw-g2vx?

O3 pinpoints whether GHSA-7m29-f4hw-g2vx 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-7m29-f4hw-g2vx actively exploited in the wild?

No public exploit code has been indexed for GHSA-7m29-f4hw-g2vx 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.

What is the EPSS score for GHSA-7m29-f4hw-g2vx?

GHSA-7m29-f4hw-g2vx has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 5th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-7m29-f4hw-g2vx?

GHSA-7m29-f4hw-g2vx is classified as CWE-1240 (CWE-1240). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-7m29-f4hw-g2vx published, and has it been updated?

GHSA-7m29-f4hw-g2vx was published on February 18, 2026 and was last updated on February 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

GHSA-7m29-f4hw-g2vx: utls

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk5th percentile+0.14%

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.

Blast Radius

1 pkg affected

🐹github.com/refraction-networking/utls

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

There is a fingerprint mismatch with Chrome when using GREASE ECH, having to do with ciphersuite selection. When Chrome selects the preferred ciphersuite in the outer ClientHello and the ciphersuite for ECH, it does so consistently based on hardware support. That means, for example, if it prefers AES for the outer ciphersuite, it would also use AES for ECH. The Chrome parrot in utls hardcodes AES preference for outer ciphersuites but selects the ECH ciphersuite randomly between AES and ChaCha20. So there is a 50% chance of selecting ChaCha20 for ECH while using AES for the outer ciphersuite, which is impossible in Chrome.

This is only a problem in GREASE ECH, since in real ECH Chrome selects the first valid ciphersuite when AES is preferred, which is the same in utls. So no change is done there.

Affected symbols: HelloChrome_120, HelloChrome_120_PQ, HelloChrome_131, HelloChrome_133

Fix commit: 24bd1e05a788c1add7f3037f4532ea552b2cee07

Thanks to telegram @acgdaily for reporting this issue.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/refraction-networking/utls`	≥ 1.6.0&&< 1.8.1	1.8.1

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/refraction-networking/utls. 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 github.com/refraction-networking/utls to 1.8.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-7m29-f4hw-g2vx 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-7m29-f4hw-g2vx 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-7m29-f4hw-g2vx. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

There is a fingerprint mismatch with Chrome when using GREASE ECH, having to do with ciphersuite selection. When Chrome selects the preferred ciphersuite in the outer ClientHello and the ciphersuite for ECH, it does so consistently based on hardware support. That means, for example, if it prefers AES for the outer ciphersuite, it would also use AES for ECH. The Chrome parrot in utls hardcodes AES preference for outer ciphersuites but selects the ECH ciphersuite randomly between AES and ChaCha20. So there is a 50% chance of selecting ChaCha20 for ECH while using AES for the outer ciphersuite, w

O3 Security · Impact-Aware SCA

Is GHSA-7m29-f4hw-g2vx in your dependencies?

O3 detects GHSA-7m29-f4hw-g2vx across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works

GHSA-7m29-f4hw-g2vx