CVE-2021-29431: SSRF in Sydent due to missing validation of hostnames
First published: Thu Apr 15 2021(Updated: )
### Impact 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. ### Patches Fixed in 9e57334, 8936925, 3d531ed, 0f00412 ### Workarounds A potential workaround would be to use a firewall to ensure that Sydent cannot reach internal HTTP resources. ### For more information If you have any questions or comments about this advisory, email us at security@matrix.org.
Credit: security-advisories@github.com security-advisories@github.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Matrix Sydent | <2.3.0 | |
| pip/matrix-sydent | <2.3.0 | 2.3.0 |
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Reference Links
- https://github.com/matrix-org/sydent/commit/0f00412017f25619bc36c264b29ea96808bf310a
- https://github.com/matrix-org/sydent/commit/3d531ed50d2fd41ac387f36d44d3fb2c62dd22d3
- https://github.com/matrix-org/sydent/commit/8936925f561b0c352c2fa922d5097d7245aad00a
- https://github.com/matrix-org/sydent/commit/9e573348d81df8191bbe8c266c01999c9d57cd5f
- https://github.com/matrix-org/sydent/releases/tag/v2.3.0
- https://github.com/matrix-org/sydent/security/advisories/GHSA-9jhm-8m8c-c3f4
- https://pypi.org/project/matrix-sydent/
- https://nvd.nist.gov/vuln/detail/CVE-2021-29431
- https://github.com/pypa/advisory-database/tree/main/vulns/matrix-sydent/PYSEC-2021-22.yaml
- https://pypi.org/project/matrix-sydent
- https://github.com/advisories/GHSA-9jhm-8m8c-c3f4 (Advisory)
Frequently Asked Questions
What is CVE-2021-29431?
CVE-2021-29431 is a vulnerability in the Matrix Sydent identity server that allows for the sending of HTTP GET requests to internal systems.
What is the severity of CVE-2021-29431?
CVE-2021-29431 has a severity rating of high with a score of 6.5.
How does CVE-2021-29431 affect Matrix Sydent?
CVE-2021-29431 affects Matrix Sydent versions up to and excluding 2.3.0.
Is it possible to exfiltrate data or control request headers with CVE-2021-29431?
No, it is not possible to exfiltrate data or control request headers with CVE-2021-29431.
How can I fix CVE-2021-29431?
To fix CVE-2021-29431, update to a version of Matrix Sydent that includes the necessary patches.
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