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GHSA-cwxw-98qj-8qjx

MediumCVSS 5.8 / 10
Published Jun 19, 2026·Last modified Jun 19, 2026
Affected Components(0)

No affected components available

Description

Impact

CookieJar incorrectly accepts cookies with a dot-only Domain attribute, such as Domain=., Domain=.., Domain=..., and whitespace-padded variants such as Domain= . . In affected versions, SetCookie::matchesDomain() removes leading dots from the cookie domain, normalizing dot-only values to the empty string; SetCookie::validate() only rejected a strictly empty domain, so these cookies could be stored and the empty normalized domain was treated as matching any request host.

An attacker-controlled origin that an application requests with a shared cookie jar can therefore set a cookie that Guzzle later sends to unrelated hosts using the same jar. This may allow cookie injection or session fixation against downstream services, depending on how those services interpret the injected cookie. Applications are affected when they use Guzzle's cookie support, for example new Client(['cookies' => true]) or an explicit shared CookieJar, and reuse the same jar across attacker-controlled and trusted origins.

Applications that do not use Guzzle's cookie support, or that use separate cookie jars per origin or trust boundary, are not affected. This issue is distinct from public suffix list validation: dot-only domains contain no domain label and should not match unrelated hosts.

Patches

The issue is patched in 7.12.1 and later. Starting in that release, Guzzle rejects dot-only cookie Domain attributes and prevents an empty normalized cookie domain from matching any request host.

Workarounds

If you cannot upgrade immediately, do not reuse the same CookieJar instance across untrusted and trusted origins. Use separate cookie jars per origin or trust boundary, or disable cookie handling for requests to untrusted hosts.

Avoid using new Client(['cookies' => true]) for clients that may contact unrelated hosts with different trust levels, because that option creates one shared jar for the client.

Risk Scores
Base Score
5.8

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The vulnerability can affect other systems as well, not just the initial system. There is a low impact on the integrity of the data.

Threat Intelligence
5.3

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.11%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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