How severe is CVE-2026-26995?

No CVSS score has been assigned to CVE-2026-26995 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-26995?

CVE-2026-26995 affects the following packages: github.com/refraction-networking/utls (Go). Ecosystems affected: Go.

How do I fix CVE-2026-26995?

Update github.com/refraction-networking/utls to 1.8.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-26995 is resolved across your whole dependency graph.

How do I detect CVE-2026-26995 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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-26995 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.

Is CVE-2026-26995 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-26995 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 CVE-2026-26995 published, and has it been updated?

CVE-2026-26995 was published on February 18, 2026 and was last updated on September 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹 Go

Not in CISA KEV

CVE-2026-26995 — utls

Fix: refraction-networking/utls@8fe0b08

CVE-2026-26995 is a security vulnerability in github.com/refraction-networking/utls. A fix is available for github.com/refraction-networking/utls — see the affected versions and patch details below.

uTLS has a fingerprint vulnerability from missing padding extension for Chrome 120

Also known asGO-2026-4512

Published

Feb 18, 2026

Updated

Sep 10, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Sep 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Real-World Exposure

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

Affected symbols: HelloChrome_120

Fix commit: 8fe0b08e9a0e7e2d08b268f451f2c79962e6acd0

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&&< 1.8.2	1.8.2`go get github.com/refraction-networking/utls@v1.8.2`

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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/refraction-networking/utls to 1.8.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-26995 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.

Frequently Asked Questions

The padding extension was incorrectly removed in utls for the non-pq variant of Chrome 120 fingerprint. Chrome removed this extension only when sending pq keyshares. Only this fingerprint is affected since newer fingerprints have pq keyshares by default and older fingerprints have this extension. Affected symbols: `HelloChrome_120` Fix commit: 8fe0b08e9a0e7e2d08b268f451f2c79962e6acd0 Thanks to telegram @acgdaily for reporting this issue.

O3 Security · Impact-Aware SCA

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