CVE-2026-67353

Medium

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.

SeverityMedium

CVSS5.3

Exploit probability—

ProductGuzzlehttp/guzzle

PublishedAug 1, 2026

First seenAug 1, 2026

Weakness typeCWE-770Allocation of resources without limits

How to fix

Update

guzzlehttp/guzzle7.15.1 or later

Vendor advisories

github.com/guzzle/guzzle/security/advisories/GHSA-f283-ghqc-fg79

Affected products

Product	Affected versions	Fixed in
guzzlehttp/guzzlePackagist	v < 7.15.1	7.15.1

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