Authentication Bypass in langgraph-api (CVE-2026-55235)
Summary
Authentication bypass in langgraph-api (CVE-2026-55235). Data can be tampered with by attackers. Exploitable via webhooks.url.disable_loopback. Mitigation: upgrade to 0.10.0 or later.
Original description
The description as published by the source.
Summary
In affected versions of langgraph-api (the LangGraph Server runtime), a run or cron could be created with a relative webhook target. When the server later delivers such a webhook, it routes the request back into the same application through an in-process loopback transport that the authentication middleware treats as internal and does not authenticate. As a result, a relative webhook target could reach the server's own routes that operate on threads and runs without the authentication context that applies to ordinary external requests.
In deployments that scope threads and runs by owner, this could allow a request associated with one user to reach routes operating on another user's thread, resulting in creation of a run on (or modification of the state of) a thread owned by another user, even where the corresponding direct external requests were correctly denied. Limited metadata from the targeted thread may be incorporated into the created run record.
We have no evidence of this behavior occurring in the wild.
Affected users / systems
You may be affected if you:
- run
langgraph-api(the LangGraph Server / Agent Server runtime, including via the LangGraph Platform Helm chart), - allow runs or crons to specify webhook targets, and
- rely on per-user authorization to separate threads and runs between users.
Impact
- Integrity: creation of a run on, or modification of the state of, a thread owned by another user, beyond the requesting user's authoriz…
Source: GitHub Security Advisories (Global) 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-2026-55235 has been found in langgraph-api.
Attackers can target a specific entry point like webhooks.url.disable_loopback over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 5.9/10.
What to do: upgrade langgraph-api to 0.10.0 or later.
If unsure, ask your IT team or search "langgraph-api CVE-2026-55235" on the vendor's site.
CVE-2026-55235 (langgraph-api) — CWE-287 / CVSS v3 5.9
Attack vector: remote (network-reachable) / no user interaction
Attack surface: webhooks.url.disable_loopback / LANGGRAPH_WEBHOOKS
Patched: 0.10.0 — 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.
Authentication bypass (CWE-287) exists in langgraph-api. Attackers reach the vulnerable code path via webhooks.url.disable_loopback.
Check the vendor advisory for the affected versions of langgraph-api. Attack surface: webhooks.url.disable_loopback / LANGGRAPH_WEBHOOKS.
Severity: Medium (CVSS 5.9/10). Data can be tampered with by attackers.
Update to 0.10.0.
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 'langgraph-api' . 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 'langgraph-api' . | 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
langgraph-api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 langgraph-api to 0.10.0ステージング環境で 0.10.0 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。
-
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。