CVE-2021-29430
What it is
Sydent is a reference Matrix identity server. Sydent does not limit the size of requests it receives from HTTP clients. A malicious user could send an HTTP request with a very large body, leading to memory exhaustion and denial of service. Sydent also does not limit response size for requests it makes to remote Matrix homeservers. A malicious homeserver could return a very large response, again leading to memory exhaustion and denial of service. This affects any server which accepts registration requests from untrusted clients. This issue has been patched by releases 89071a1, 0523511, f56eee3. As a workaround request sizes can be limited in an HTTP reverse-proxy. There are no known workarounds for the problem with overlarge responses.
At a glance
- Exploitability
- Can be exploited over the network without logging in. High risk of service disruption.
- Exploit odds
- 1.8% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 1.8% in the next 30 days (EPSS).
- Severity: 7.5 HIGH (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 1.8% · EPSS, next 30 days
- Weakness
- CWE-20 · Improper input validation
- Record status
- Modified
Affected
- Matrix Sydent < 2.3.0
Attack profile CVSS 3.1 · 7.5
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2021-29430.md and follow it. Check whether this project is affected by CVE-2021-29430. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://github.com/matrix-org/sydent/commit/0523511d2fb40f2738f8a8549868f44b96e5dab7
- https://github.com/matrix-org/sydent/commit/89071a1a754c69a50deac89e6bb74002d4cda19d
- https://github.com/matrix-org/sydent/commit/f56eee315b6c44fdd9f6aa785cc2ec744a594428
- https://github.com/matrix-org/sydent/releases/tag/v2.3.0
- https://github.com/matrix-org/sydent/security/advisories/GHSA-wmg4-8cp2-hpg9
- https://github.com/matrix-org/sydent/commit/0523511d2fb40f2738f8a8549868f44b96e5dab7
- https://github.com/matrix-org/sydent/commit/89071a1a754c69a50deac89e6bb74002d4cda19d
- https://github.com/matrix-org/sydent/commit/f56eee315b6c44fdd9f6aa785cc2ec744a594428
- https://github.com/matrix-org/sydent/releases/tag/v2.3.0
- https://github.com/matrix-org/sydent/security/advisories/GHSA-wmg4-8cp2-hpg9
References
- https://github.com/matrix-org/sydent/commit/0523511d2fb40f2738f8a8549868f44b96e5dab7
- https://github.com/matrix-org/sydent/commit/89071a1a754c69a50deac89e6bb74002d4cda19d
- https://github.com/matrix-org/sydent/commit/f56eee315b6c44fdd9f6aa785cc2ec744a594428
- https://github.com/matrix-org/sydent/releases/tag/v2.3.0
- https://github.com/matrix-org/sydent/security/advisories/GHSA-wmg4-8cp2-hpg9
- https://pypi.org/project/matrix-sydent/
- https://github.com/matrix-org/sydent/commit/0523511d2fb40f2738f8a8549868f44b96e5dab7
- https://github.com/matrix-org/sydent/commit/89071a1a754c69a50deac89e6bb74002d4cda19d
- https://github.com/matrix-org/sydent/commit/f56eee315b6c44fdd9f6aa785cc2ec744a594428
- https://github.com/matrix-org/sydent/releases/tag/v2.3.0
- https://github.com/matrix-org/sydent/security/advisories/GHSA-wmg4-8cp2-hpg9
- https://pypi.org/project/matrix-sydent/