Vulnerability in Mastodon (CVE-2026-50129)
Summary
Vulnerability in Mastodon (CVE-2026-50129). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 4.5.11 or later.
Original description
The description as published by the source.
Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.11, 4.4.18, and 4.3.24, a DoS can be triggered by (Uncaught Exception vulerability), due to missing exception handling in the math sanitizer. Malformed nodes can result in a DoS of a whole server or targeted users services, depending on the type of action that includes the malformed nodes and the services interacting with it. This vulnerability is fixed in 4.5.11, 4.4.18, and 4.3.24.
Source: NIST National Vulnerability Database NVD GitHub Advisory
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-2026-50129 has been found in Mastodon.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade Mastodon to 4.5.11 or later.
If unsure, ask your IT team or search "Mastodon CVE-2026-50129" on the vendor's site.
CVE-2026-50129 (Mastodon) — CWE-248 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 4.5.11 — 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.
A vulnerability (CWE-248) exists in Mastodon.
Check the vendor advisory for the affected versions of Mastodon.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 4.5.11.
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 'Mastodon' . 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
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1Identify exposure identify
grep -r 'Mastodon' . | 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
Mastodon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 Mastodon to 4.5.11ステージング環境で 4.5.11 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。
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov