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CVE-2021-32659

Vulnerability in matrix-appservice-bridge (CVE-2021-32659)

Summary

Vulnerability in matrix-appservice-bridge (CVE-2021-32659). Confidential information can be exposed externally. Exploitable via roomUpgradeOpts. Mitigation: upgrade to 2.6.1 or later.

Original description

The description as published by the source.

Impact

If a bridge has room upgrade handling turned on in the configuration (the roomUpgradeOpts key when instantiating a new Bridge instance.), any m.room.tombstone event it encounters will be used to unbridge the current room and bridge into the target room. However, the target room m.room.create event is not checked to verify if the predecessor field contains the previous room. This means that any mailcious admin of a bridged room can repoint the traffic to a different room without the new room being aware.

Patches

Versions 2.6.1 and greater are patched.

Workarounds

Disabling the automatic room upgrade handling can be done by removing the roomUpgradeOpts key from the Bridge class options.

References

The issue is patched by https://github.com/matrix-org/matrix-appservice-bridge/pull/330

For more information]

If you have any questions or comments about this advisory, email 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-2021-32659 has been found in matrix-appservice-bridge.
Attackers can target a specific entry point like roomUpgradeOpts over the network to misuse the product.
Confidential information can be exposed externally.
What to do: upgrade matrix-appservice-bridge to 2.6.1 or later.
If unsure, ask your IT team or search "matrix-appservice-bridge CVE-2021-32659" on the vendor's site.

CVE-2021-32659 (matrix-appservice-bridge) — CWE-306
Attack vector: remote (network-reachable) / no user interaction
Attack surface: roomUpgradeOpts / Bridge / m.room.tombstone / m.room.create
Patched: 2.6.1 — apply immediately
Workaround: Disabling the automatic room upgrade handling can be done by removing the roomUpgradeOpts key from the Bridge class options.
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.

❓ What is the problem

A vulnerability (CWE-306) exists in matrix-appservice-bridge. Attackers reach the vulnerable code path via roomUpgradeOpts.

📍 Affected scope

Check the vendor advisory for the affected versions of matrix-appservice-bridge. Attack surface: roomUpgradeOpts / Bridge / m.room.tombstone / m.room.create.

🔥 Severity

Severity: ?. Confidential information can be exposed externally.

🔧 How to fix

Update to 2.6.1.

🛡️ Workaround

Workaround: Disabling the automatic room upgrade handling can be done by removing the roomUpgradeOpts key from the Bridge class options.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'matrix-appservice-bridge' . 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

  1. 1
    Identify exposure identify 
    grep -r 'matrix-appservice-bridge' . | 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-appservice-bridge を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply temporary workaround mitigate 
    Disabling the automatic room upgrade handling can be done by removing the `roomUpgradeOpts` key from the `Bridge` class options.

    パッチが適用されるまでの応急処置として、Disabling the automatic room upgrade handling can be done by removing the roomUpgradeOpts key from the Bridge class options. を実施。回避策の副作用 (機能低下) を確認した上で。

  3. 3
    Apply patch patch 
    Upgrade matrix-appservice-bridge to 2.6.1

    ステージング環境で 2.6.1 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。

  4. 4
    Post-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

npm matrix-appservice-bridge
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.6.1"}]}]

References

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