CVE-2026-55235 json
langgraph-api: Relative webhook targets in LangGraph Server can reach in-process routes without authentication
published 2026-08-19 2 mo ago modified 2026-10-28 11 d ago also GHSA-2c9q-c2q9-qgqv , PYSEC-2026-3857 , EUVD-2026-77585
- cvss
- 5.9
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 30%
- public exploits
- 0
- none known
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.
Patch / fix
- pypi langgraph-api 0.10.0
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 53 d ago
Exploit prediction
0.36% chance of exploitation in the next 30 days, higher than 30% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 5.9 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L |
| OSV | 3.1 | 5.9 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L |
| GitHub | 3.1 | 5.9 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | langgraph-api | <0.10.0 |
0.10.0 |
Affected products
- langchain-ai langgraph-api
Classification
- Weakness
-
- CWE-287 Improper Authentication
References
-
github.com
/langchain-ai/helm/security/advisories/GHSA-2c9q-c2q9-qgqv
web
-
github.com
/langchain-ai/docs/blob/7b70fbacab21f84d9c6f9848f86cdeb471adbb50/src/langsmith/agent-server-changelog.mdx
web
-
nvd.nist.gov
/vuln/detail/CVE-2026-55235
advisory
-
github.com
/langchain-ai/helm
package
-
github.com
/pypa/advisory-database/tree/main/vulns/langgraph-api/PYSEC-2026-3857.yaml
web
-
pypi.org
/project/langgraph-api
package
-
github.com
/advisories/GHSA-2c9q-c2q9-qgqv
advisory
Sources
- CVE List CVE-2026-55235
- GitHub Advisory GHSA-2c9q-c2q9-qgqv
- NVD CVE-2026-55235
- OSV PYSEC-2026-3857
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.