Path Traversal in matrix-synapse (CVE-2021-41281)
Summary
Path traversal in matrix-synapse (CVE-2021-41281). Data can be tampered with by attackers. Mitigation: upgrade to 1.47.1 or later.
Original description
The description as published by the source.
Impact
Synapse instances with the media repository enabled can be tricked into downloading a file from a remote server into an arbitrary directory, potentially outside the media store directory.
The last two directories and file name of the path are chosen randomly by Synapse and cannot be controlled by an attacker, which limits the impact.
Homeservers with the media repository disabled are unaffected. Homeservers configured with a federation whitelist are also unaffected.
Patches
Server administrators should upgrade to 1.47.1 or later.
Workarounds
Server administrators using a reverse proxy could, at the expense of losing media functionality, block the following endpoints:
/_matrix/media/r0/download/{serverName}/{mediaId}/_matrix/media/r0/download/{serverName}/{mediaId}/{fileName}/_matrix/media/r0/thumbnail/{serverName}/{mediaId}
Alternatively, non-containerized deployments can be adapted to use the hardened systemd config, located at contrib/systemd/override-hardened.conf.
References
n/a
For more information
If you have any questions or comments about this advisory, e-mail us at security@matrix.org.
Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2021-41281 has been found in matrix-synapse.
Data can be tampered with by attackers.
What to do: upgrade matrix-synapse to 1.47.1 or later.
If unsure, ask your IT team or search "matrix-synapse CVE-2021-41281" on the vendor's site.
CVE-2021-41281 (matrix-synapse) — CWE-22
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 1.47.1 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Path traversal (CWE-22) exists in matrix-synapse.
Check the vendor advisory for the affected versions of matrix-synapse.
Severity: ?. Data can be tampered with by attackers.
Update to 1.47.1.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'matrix-synapse' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'matrix-synapse' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
matrix-synapseを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade matrix-synapse to 1.47.1ステージング環境で 1.47.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2021-41281 matrix-synapse Fixed in: 1.47.1-1
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com
- web lists.fedoraproject.org
- web lists.fedoraproject.org