CVE-2021-29431

SSRF in Sydent due to missing validation of hostnames

Description

Sydent is a reference Matrix identity server. Sydent can be induced to send HTTP GET requests to internal systems, due to lack of parameter validation or IP address blacklisting. It is not possible to exfiltrate data or control request headers, but it might be possible to use the attack to perform an internal port enumeration. This issue has been addressed in in 9e57334, 8936925, 3d531ed, 0f00412. A potential workaround would be to use a firewall to ensure that Sydent cannot reach internal HTTP resources.

Category

7.7
CVSS
Severity: High
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.30%
Third-Party Advisory github.com Third-Party Advisory github.com Third-Party Advisory github.com Third-Party Advisory github.com Third-Party Advisory github.com Third-Party Advisory github.com Third-Party Advisory pypi.org
Affected: matrix-org sydent
Published at:
Updated at:

References

Frequently Asked Questions

What is the severity of CVE-2021-29431?
CVE-2021-29431 has been scored as a high severity vulnerability.
How to fix CVE-2021-29431?
To fix CVE-2021-29431, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-29431 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2021-29431 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-29431?
CVE-2021-29431 affects matrix-org sydent.
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