CVE-2026-69245: Session Fixation (CVSS 6.5)

Description

Guzzle is an extensible PHP HTTP client. Prior to 7.15.2 and 8.0.1, SetCookie::matchesDomain() gives every subdomain of a cookie Domain that cookie unless SetCookie::matchesDomain() recognizes the Domain as an IP literal or a numeric host, and the decision comes from the domain's own text, so two spellings a transport reads as an address keep subdomain scope. Hexadecimal and mixed-base forms such as 0x7f000001 and 0177.0.0.0x1 go unrecognized while libcurl 8.21.0 reads both as 127.0.0.1. A percent-escaped Domain keeps that scope on both branches because percent-decoding sits above numeric parsing, so 192.168.0.%31 and 127.0.0.1%2e are registered names in the URI grammar rather than address literals, and no numeric rule in any base classifies them, while libcurl decodes the host before resolving and reads them as 192.168.0.1 and 127.0.0.1. A cookie stored for Domain=0x7f000001 is placed in the Cookie header of a request to evil.0x7f000001, disclosing a session identifier or token to a host that is not that address, and a response from evil.0x7f000001 setting Domain=0x7f000001 is accepted into the jar and replayed to the address, so a server answering for the look-alike name can fix a session or set application state. Exploitation requires the application to enable cookie support, address an origin by one of these spellings, and contact a host whose name ends in that spelling. This issue is fixed in versions 7.15.2 and 8.0.1.

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CVSS v3.1 Score

6.5

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS — Exploit Prediction

0.0014

Probability of exploitation

0.04%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-180 CWE-180

CWE-346 CWE-346

CWE-384 CWE-384

References

Other References

https://github.com/guzzle/guzzle/commit/3aeea0406aab88cbbd86531313d7cebf8ae149a4 https://github.com/guzzle/guzzle/commit/744101956d78b7c1384d0cbf379db13e859167bf https://github.com/guzzle/guzzle/pull/3907 https://github.com/guzzle/guzzle/pull/3908 https://github.com/guzzle/guzzle/releases/tag/7.15.2 https://github.com/guzzle/guzzle/releases/tag/8.0.1 https://github.com/guzzle/guzzle/security/advisories/GHSA-f7vp-7xgx-4w4r

Frequently Asked Questions

What is CVE-2026-69245? +

Guzzle is an extensible PHP HTTP client. Prior to 7.15.2 and 8.0.1, SetCookie::matchesDomain() gives every subdomain of a cookie Domain that cookie unless SetCookie::matchesDomain() recognizes the Domain as an IP literal or a numeric host, and the decision comes from the domain's own text, so two spellings a transport reads as an address keep subdomain scope. Hexadecimal and mixed-base forms such as 0x7f000001 and 0177.0.0.0x1 go unrecognized while libcurl 8.21.0 reads both as 127.0.0.1. A percent-escaped Domain keeps that scope on both branches because percent-decoding sits above numeric parsing, so 192.168.0.%31 and 127.0.0.1%2e are registered names in the URI grammar rather than address literals, and no numeric rule in any base classifies them, while libcurl decodes the host before resolving and reads them as 192.168.0.1 and 127.0.0.1. A cookie stored for Domain=0x7f000001 is placed in the Cookie header of a request to evil.0x7f000001, disclosing a session identifier or token to a host that is not that address, and a response from evil.0x7f000001 setting Domain=0x7f000001 is accepted into the jar and replayed to the address, so a server answering for the look-alike name can fix a session or set application state. Exploitation requires the application to enable cookie support, address an origin by one of these spellings, and contact a host whose name ends in that spelling. This issue is fixed in versions 7.15.2 and 8.0.1. It has a CVSS v3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2026-69245? +

CVE-2026-69245 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0014, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-69245? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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