{"cve":"CVE-2021-29433","nvd":{"published":"2021-04-15T18:15:12.497","modified":"2026-06-17T03:47:37.947","status":"Modified","description":"Sydent is a reference Matrix identity server. In Sydent versions 2.2.0 and prior, sissing input validation of some parameters on the endpoints used to confirm third-party identifiers could cause excessive use of disk space and memory leading to resource exhaustion. A patch for the vulnerability is in version 2.3.0. No workarounds are known to exist.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L","score":4.3},"cwes":["CWE-400","CWE-20"],"references":["https://github.com/matrix-org/sydent/commit/3175fd358ebc2c310eab7a3dbf296ce2bd54c1da","https://github.com/matrix-org/sydent/security/advisories/GHSA-pw4v-gr34-2553","https://github.com/matrix-org/sydent/commit/3175fd358ebc2c310eab7a3dbf296ce2bd54c1da","https://github.com/matrix-org/sydent/security/advisories/GHSA-pw4v-gr34-2553"],"products":["matrix:sydent"],"source":"nvd","synced_at":"2026-10-19T21:17:01.373894544+00:00"},"epss":{"cve":"CVE-2021-29433","score":0.00927,"percentile":0.60509,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-pw4v-gr34-2553","url":"https://osv.dev/vulnerability/GHSA-pw4v-gr34-2553","summary":"Sydent DoS (via resource exhaustion) due to improper input validation","modified":"2026-09-10T03:49:03.750308427Z","packages":[{"ecosystem":"PyPI","name":"matrix-sydent","purl":"pkg:pypi/matrix-sydent","ranges":["<2.3.0"],"fixed":["2.3.0"]}]},{"id":"PYSEC-2021-24","url":"https://osv.dev/vulnerability/PYSEC-2021-24","summary":"","modified":"2023-11-08T04:05:33.835170Z","packages":[{"ecosystem":"PyPI","name":"matrix-sydent","purl":"pkg:pypi/matrix-sydent","ranges":["<2.3.0"],"fixed":["2.3.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}