SSRF in Sydent due to missing validation of hostnames
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.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | matrix-sydent | < 2.3.0 | 2.3.0 |
References
- https://github.com/matrix-org/sydent/commit/3d531ed50d2fd41ac387f36d44d3fb2c62dd22d3
- https://github.com/matrix-org/sydent/commit/0f00412017f25619bc36c264b29ea96808bf310a
- https://github.com/matrix-org/sydent/security/advisories/GHSA-9jhm-8m8c-c3f4
- https://github.com/matrix-org/sydent/commit/9e573348d81df8191bbe8c266c01999c9d57cd5f
- https://github.com/matrix-org/sydent/commit/8936925f561b0c352c2fa922d5097d7245aad00a
- https://pypi.org/project/matrix-sydent/
- https://github.com/matrix-org/sydent/releases/tag/v2.3.0
- https://nvd.nist.gov/vuln/detail/CVE-2021-29431
- https://github.com/matrix-org/sydent
- https://github.com/pypa/advisory-database/tree/main/vulns/matrix-sydent/PYSEC-2021-22.yaml
- https://pypi.org/project/matrix-sydent
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N- Weakness (CWE)
CWE-20, CWE-918- Platform
- Python (PyPI)
- Package
matrix-sydent- Disclosed
- 15.04.2021
- Updated
- 11.10.2026 15:17
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2021-22 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-9jhm-8m8c-c3f4 - CC BY 4.0
Vulnerability history: matrix-sydent
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 7
- First → latest
- 05.2019 07.2023
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 1
- High 2
- Medium 4
Disclosures per year
- 2019: 1
- 2020: 0
- 2021: 4
- 2022: 1
- 2023: 1
- 2024: 0
- 2025: 0
- 2026: 0
-
SSRF in Sydent due to missing validation of hostnames this entry
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