Vulnerability in matrix-synapse (CVE-2020-26890)
Summary
Vulnerability in matrix-synapse (CVE-2020-26890). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 1.20.0 or later.
Original description
The description as published by the source.
Impact
A denial of service attack against Matrix clients can be exploited by sending an event including invalid JSON data to Synapse. Synapse would relay the data to clients which could crash or hang. Impact is long-lasting if the event is made part of the room state.
Patches
At a minimum #8106 and #8291 must be applied. #7372 and #8124 include additional checks.
Workarounds
There are no known workarounds.
Upgrading notes
If an invalid event is accepted by an earlier Synapse it can become part of the room state and will not be fixed by upgrading Synapse. Redacting the invalid event should avoid clients receiving the invalid event.
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-2020-26890 has been found in matrix-synapse.
Risk of unauthorized operations or information disclosure.
What to do: upgrade matrix-synapse to 1.20.0 or later.
If unsure, ask your IT team or search "matrix-synapse CVE-2020-26890" on the vendor's site.
CVE-2020-26890 (matrix-synapse) — CWE-20
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 1.20.0 — apply immediately
Workaround: There are no known workarounds.
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.
A vulnerability (CWE-20) exists in matrix-synapse.
Check the vendor advisory for the affected versions of matrix-synapse.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 1.20.0.
Workaround: There are no known workarounds.
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 temporary workaround mitigate
There are no known workarounds.パッチが適用されるまでの応急処置として、There are no known workarounds. を実施。回避策の副作用 (機能低下) を確認した上で。
-
3Apply patch patch
Upgrade matrix-synapse to 1.20.0ステージング環境で 1.20.0 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。
-
4Post-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-2020-26890 matrix-synapse Fixed in: 1.20.0-1
References
- advisory nvd.nist.gov
- package github.com
- web lists.fedoraproject.org
- web lists.fedoraproject.org
- web github.com
- web github.com
- web lists.fedoraproject.org
- web lists.fedoraproject.org
- web pypi.org