Quick answers
- Is This vulnerability exploited in the wild?
- No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.
- How severe is This vulnerability?
- Medium severity, with a CVSS score of 5.9, published 1 August 2026.
- Which products and versions are affected?
- Guzzle < 7.15.1; guzzlehttp/guzzle (Packagist) < 7.15.1.
- Is there a fix for This vulnerability?
- A patch was published on 2026-08-04: Fix confirmed in version 7.15.1 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is This vulnerability attacked?
- It is attacked over the network, in a software library.
- Am I affected?
- Check whether you run Guzzle or guzzlehttp/guzzle (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
Guzzle versions before 7.15.1 fail to correctly implement host-only cookie semantics in the CookieJar component. When a response cookie is received without a Domain attribute (or an empty one), it should be restricted to the exact originating host. Instead, Guzzle stores the request host in the cookie's Domain field and applies standard domain-matching rules, causing the cookie to be sent to subdomains. An attacker controlling a child host can capture these cookies if the same cookie jar is reused across trust boundaries. The issue is resolved in version 7.15.1, which introduces a HostOnly marker for stored cookies.
Affected products
- guzzlehttp guzzle < 7.15.1
Timeline
- 2026-07-18: advisory: Original advisory GHSA-wm3w-8rrp-j577 published
- 2026-08-01: disclosed: CVE-2026-67355 published
- 2026-08-04: patched: Fix confirmed in version 7.15.1