Vulnerability · Published Aug 1, 2026 · Assigned by VulnCheck

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

Medium 5.3

In plain English

A medium-severity resource allocation without limits in guzzle from guzzle. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 36% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.3Medium

Exploit odds (30 days)0.4%top 63.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	guzzle	no fix listed	DEBIAN-CVE-2026-67353
Debian:13	guzzle	no fix listed	DEBIAN-CVE-2026-67353
Debian:14	guzzle	7.15.1-1	DEBIAN-CVE-2026-67353
Packagist	guzzlehttp/guzzle	7.15.1	GHSA-f283-ghqc-fg79
Ubuntu:24.04:LTS	guzzle	no fix listed	UBUNTU-CVE-2026-67353
Ubuntu:26.04:LTS	guzzle	no fix listed	UBUNTU-CVE-2026-67353
Ubuntu:26.10	guzzle	no fix listed	UBUNTU-CVE-2026-67353

Affected products (as reported)

Vendor	Product	Versions
guzzle	guzzle	0 – before 7.15.1

Weakness: CWE-770 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

References

GitHub Security Advisory (GHSA-f283-ghqc-fg79) vendor-advisory
VulnCheck Advisory: guzzlehttp/guzzle before 7.15.1 Unbounded Cookie Denial of Service third-party-advisory