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GHSA-q3j3-w37x-hq2q
No affected components available
Description
When a Symfony application is running behind a proxy or a load-balancer, you can tell Symfony to look for the X-Forwarded-* HTTP headers. HTTP headers that are not part of the "trusted_headers" allowed list are ignored and protect you from "Cache poisoning" attacks.
In Symfony 5.2, we've added support for the X-Forwarded-Prefix header, but this header was accessible in sub-requests, even if it was not part of the "trusted_headers" allowed list. An attacker could leverage this opportunity to forge requests containing a X-Forwarded-Prefix HTTP header, leading to a web cache poisoning issue.
Resolution
Symfony now ensures that the X-Forwarded-Prefix HTTP header is not forwarded to sub-requests when it is not trusted.
The patch for this issue is available here for branch 5.3.
Credits
We would like to thank Soner Sayakci for reporting the issue and Jérémy Derussé for fixing the issue.
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. 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 high impact on the integrity of the data.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
Probability that this vulnerability will be exploited in the wild within the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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