Guzzle: Proxy-Authorization headers can be sent to origin servers

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

• CISA KEV Not listed.
• EPSS 0.0037, the 31st percentile, on 11 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

1. 14 Jul 2026, 18:17 UTC Published by the maintainers as a GitHub repository advisory
2. 31 Oct 2026, 13:57 UTC First seen by agentprime
3. 31 Oct 2026, 13:57 UTC Confirmed by OSV

Sources

• GitHub Advisory Database: GHSA-94pj-82f3-465w
• OSV: GHSA-94pj-82f3-465w
• github.com/guzzle/guzzle/security/advisories/GHSA-94pj-82f3-465w
• nvd.nist.gov/vuln/detail/CVE-2026-67339
• github.com/guzzle/guzzle/pull/3876
• github.com/guzzle/guzzle/commit/9e4580d4b9981e903dc6323fe37f50a96e85b05e
• github.com/guzzle/guzzle
• github.com/guzzle/guzzle/releases/tag/7.14.2
• www.vulncheck.com/advisories/guzzlehttp-guzzle-before-proxy-authorization-header-disclosure

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.