What is CVE-2026-67355?

CVE-2026-67355 is a medium-severity vulnerability in Guzzle, classified under Insertion of Sensitive Information into Sent Data. CVSS score: 5.9/10. Published 2026-08-01.

How severe is CVE-2026-67355?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Vulnerability in Guzzle

CVE-2026-67355

guzzlehttp/guzzle versions before 7.15.1 fail to preserve host-only cookie scope, storing the request host in the Domain field instead of marking cookies as host-only. Attackers controlling child hosts can receive host-only cookies intende…

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.

Affected products

Guzzle — versions 0, 7.15.1

Weakness classification (CWE)

CWE-201 — Insertion of Sensitive Information into Sent Data

References

disclosure@vulncheck.com (vendor-advisory)
disclosure@vulncheck.com (third-party-advisory)

Frequently asked questions

What is CVE-2026-67355?: CVE-2026-67355 is a medium-severity vulnerability in Guzzle, classified under Insertion of Sensitive Information into Sent Data. CVSS score: 5.9/10. Published 2026-08-01.
How severe is CVE-2026-67355?: Medium severity. CVSS v3 base score is 5.9 out of 10.