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GHSA-q7jf-gf43-6x6p

MediumCVSS 4.2 / 10
Published Oct 24, 2025·Last modified Nov 27, 2025
Affected Components(0)

No affected components available

Description

Summary

A flaw in the CORS middleware allowed request Vary headers to be reflected into the response, enabling attacker-controlled Vary values and potentially affecting cache behavior.

Details

The middleware previously copied the Vary header from the request when origin was not set to "*". Since Vary is a response header that should only be managed by the server, this could allow an attacker to influence caching behavior or cause inconsistent CORS handling.

Most environments will see impact only when shared caches or proxies rely on the Vary header. The practical effect varies by configuration.

Impact

May cause cache key pollution and inconsistent CORS enforcement in certain setups. No direct confidentiality, integrity, or availability impact in default configurations.

Resolution

Update to the latest patched release. The CORS middleware has been corrected to handle Vary exclusively as a response header.

Risk Scores
Base Score
4.2

The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker does not need any special privileges or access rights. The attacker needs the user to perform some action, like clicking a link. The impact is confined to the system where the vulnerability exists. There is a low impact on the confidentiality of the information. There is a low impact on the integrity of the data.

Threat Intelligence
3.9

Limited exploitation activity has been observed. Close monitoring and planned remediation are recommended.

EPSS
0.28%

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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