CVE-2026-67354: Guzzle

Medium severity, CVSS 5.9. EPSS: 0.4% chance of exploitation in the next 30 days.

guzzlehttp/guzzle versions before 7.15.1 contain an information disclosure vulnerability in RedirectMiddleware. When the optional allow_redirects.referer setting is enabled, the middleware copies the URI fragment (the portion after '#') from the referring request into the generated Referer header when following a same-scheme redirect (e.g., HTTPS to HTTPS). An attacker who controls the redirect destination can read this fragment from the incoming Referer header, potentially disclosing one-time login secrets, access tokens, state values, or other sensitive client data to a server never meant to receive it. The referer setting is disabled by default. Fixed in 7.15.1, which strips the fragment before generating the Referer value.

Affected products

• Guzzle Guzzle: before 7.15.1 (fixed in 7.15.1)

Published 2026-08-01. Last modified 2026-10-08.