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VulnerabilityPublished Updated

CVE-2026-55235: langchain-ai langgraph-api · Improper Authentication

Affects langchain-ai langgraph-apiSource CVE Database V5

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Not known to be exploited · CVSS 5.9 Medium : upgrade to 0.10.0 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
5.9Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 30% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 0.10.0
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 14 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade langgraph-api and langchain-ai/langgraph-api to 0.10.0.

Affected software

ProductAffectedFixed in
langchain-ailanggraph-apiAffected
  • <0.10.0
Fixed in
  • 0.10.0
GitHublangchain-ai/langgraph-apipkg:github/langchain-ai/langgraph-apiOther threatsAffected
  • <0.10.0
Fixed in
  • 0.10.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade langgraph-api to version 0.10.0 or later, where this issue is fixed. Deployments that deliberately re-enable loopback delivery should restrict it to controlled same-process routes to avoid unauthenticated webhook requests. No other mitigation is indicated by the vendor advisory.

Description

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.

References

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