Resource exhaustion in Matrix Sydent
CVE-2021-29430
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.
Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.018 (78.0th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 78th percentile — 78.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.018 · newest: 0.018 · change: 0.000
Affected products
- Matrix Sydent
- Matrix-Org Sydent — versions < 2.3.0
Weakness classification (CWE)
References
- pypi.org/project/matrix-sydent/ (Product, Third Party Advisory)
- github.com/matrix-org/sydent/security/advisories/GHSA-wmg4-8cp2-hpg9 (Patch, Third Party Advisory)
- github.com/matrix-org/sydent/commit/89071a1a754c69a50deac89e6bb74002d4cda19d (Patch, Third Party Advisory)
- github.com/matrix-org/sydent/commit/0523511d2fb40f2738f8a8549868f44b96e5dab7 (Patch, Third Party Advisory)
- github.com/matrix-org/sydent/commit/f56eee315b6c44fdd9f6aa785cc2ec744a594428 (Patch, Third Party Advisory)
- github.com/matrix-org/sydent/releases/tag/v2.3.0 (Third Party Advisory, Release Notes)
Frequently asked questions
- What is CVE-2021-29430?
- CVE-2021-29430 is a high-severity vulnerability in Matrix Sydent, classified under Improper Input Validation. CVSS score: 7.5/10. Published 2021-04-15.
- How severe is CVE-2021-29430?
- High severity. CVSS v3 base score is 7.5 out of 10.