CVE-2026-67339 guzzlehttp/guzzle before 7.14.2 Proxy-Authorization Header Disclosure
Attackers can capture proxy credentials via origin server logs due to improper header isolation in Guzzle HTTP client.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-67339?
CVE-2026-67339 is a medium-severity vulnerability in guzzle, published on 1 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
guzzlehttp/guzzle versions before 7.14.2 fail to properly isolate Proxy-Authorization headers from origin servers in cURL handlers. Attackers can capture proxy credentials through origin server access logs when requests are redirected, bypassed, or sent through SOCKS proxies that Guzzle misclassifies as direct connections.
Weakness: CWE-200
Which versions are affected by CVE-2026-67339?
2 open source packages ship an affected version, including guzzlehttp/guzzle.
| Package | Affected | Fixed in |
|---|---|---|
guzzlehttp/guzzle Packagist | All versions | 7.14.2 |
guzzlehttp/guzzle Packagist | All versions | 7.14.2 |
How do I fix CVE-2026-67339?
Upgrade guzzlehttp/guzzle to 7.14.2 or later.
Is CVE-2026-67339 being exploited?
There is no known exploitation of CVE-2026-67339 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-67339, GHSA-94pj-82f3-465w, MINI-7xqg-x9f6-3577, MINI-c626-94jx-5wrm, MINI-c6hq-hvvq-rhx8, MINI-j5pr-65xp-f2f3 and 5 more.