langgraph-api: Relative webhook targets in LangGraph Server can reach in-process routes without authentication
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- High
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- None · High · Low
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-287.
Summary
langgraph-api implements the LangGraph API for rapid development and testing. Prior to 0.10.0, langgraph-api permits a run or cron to specify a relative webhook target that is delivered through an in-process loopback transport, and the authentication middleware treats that transport as internal without applying the authentication context used for external requests. In deployments that rely on per-user authorization to separate threads and runs, an authenticated user can direct a webhook to the server's own thread and run routes, allowing creation of a run on or modification of another user's thread and limited incorporation of the targeted thread's metadata into the created run record. The affected path requires webhook targets and per-user authorization boundaries; deployments that deliberately re-enable loopback delivery should restrict it to controlled same-process routes because those webhooks remain unauthenticated. This issue is fixed in version 0.10.0.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| langchain-ai | langgraph-api | before 0.10.0 | 0.10.0 | Patch available | CNA |
| — | langgraph-api (PyPI) | before 0.10.0 | 0.10.0 | Patch available | GHSA-2c9q-c2q9-qgqv |
- langgraph-api Vendorlangchain-ai Affected before 0.10.0 Fixed in 0.10.0 Patch available CNA
- langgraph-api (PyPI) Vendor— Affected before 0.10.0 Fixed in 0.10.0 Patch available GHSA-2c9q-c2q9-qgqv
Remediation
- Fix · CNA langgraph-api (langchain-ai) Fixed in 0.10.0
- Fix · GHSA-2c9q-c2q9-qgqv langgraph-api (PyPI) Fixed in 0.10.0 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-55235
- 2026-10-03 Alias added: GHSA-2c9q-c2q9-qgqv
- 2026-10-28 3 new references · GHSA-2c9q-c2q9-qgqv
References
Other 4
- https://github.com/langchain-ai/helm/security/advisories/GHSA-2c9q-c2q9-qgqv
- https://github.com/langchain-ai/docs/blob/7b70fbacab21f84d9c6f9848f86cdeb471adbb50/src/langsmith/agent-server-changelog.mdx
- https://github.com/langchain-ai/helm
- https://github.com/pypa/advisory-database/tree/main/vulns/langgraph-api/PYSEC-2026-3857.yaml
More langchain-ai vulnerabilities
- TI-2024-31340 langchain_experimental (aka LangChain Experimental) 0.1.17 through 0.3.0 for LangChain… CVSS 3.1CRITICAL 9.8
- TI-2023-20724 An issue in langchain langchain-ai v.0.0.232 and before allows a remote attacker to… CVSS 3.1CRITICAL 9.8
- TI-2023-20706 An issue in LanChain-ai Langchain v.0.0.245 allows a remote attacker to execute arbitrary… CVSS 3.1CRITICAL 9.8
- TI-2023-20166 An issue in Harrison Chase langchain v.0.0.194 and before allows a remote attacker to… CVSS 3.1CRITICAL 9.8
- TI-2023-20136 An issue in LangChain v.0.0.231 allows a remote attacker to execute arbitrary code via the prompt parameter. CVSS 3.1CRITICAL 9.8
- TI-2023-18185 An issue in langchain v.0.0.171 allows a remote attacker to execute arbitrary code via a… CVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-55235 · CVE Program
- CVE-2026-55235 · NVD
- FIRST EPSS
- GHSA-2c9q-c2q9-qgqv · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences