What’s Vulnerable › Vulnerabilities

CVE-2026-67353: guzzlehttp/guzzle before 7.15.1 Unbounded Cookie Denial of Service

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-01 · updated 2026-10-08
• Weakness: CWE-770

Description

guzzlehttp/guzzle versions before 7.15.1 contain a denial of service vulnerability in the CookieJar that accepts unlimited Set-Cookie header fields with no size restrictions. Attackers can return many large cookies from a malicious server, causing Guzzle to store excessive data in memory and generate oversized Cookie headers that fail in handlers or destination servers.

Affected products

• Packagist Guzzlehttp/Guzzle: before 7.15.1; 4.0.0, 4.0.0-rc.1, 4.0.0-rc.2, 4.0.1, 4.0.2, 4.1.0 (+168) — fixed in 7.15.1
• guzzle: before 7.15.1 — fixed in 7.15.1

How to fix

Upgrade to a fixed version: Packagist Guzzlehttp/Guzzle 7.15.1; guzzle 7.15.1. Check the vendor advisory for mitigations.

References

• https://github.com/guzzle/guzzle/security/advisories/GHSA-f283-ghqc-fg79
• https://www.vulncheck.com/advisories/guzzlehttp-guzzle-before-unbounded-cookie-denial-of-service

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