CVE-2026-118667: LangGraph: Unencoded identifiers in LangGraph SDK v3 streaming can redirect authenticated GET requests
Summary
The LangGraph Python SDK v3 streaming client interpolates caller-supplied threadid and assistantid values into request paths without encoding them at four synchronous and asynchronous call sites. Relative path segments can therefore redirect an authenticated GET request to another path on the same configured server.
Details
The affected gettree and fetchstate implementations build request paths from raw identifiers rather than passing each identifier through the SDK's existing quotepathparam helper. HTTP path normalization can collapse values containing relative segments before dispatch while retaining the client's authentication headers.
langgraph-sdk versions 0.4.0 through 0.4.5 are affected. The v3 stream module is not present in the 0.3.x release line.
RemoteGraph v3 streaming in langgraph 1.2.3 and later is also affected when used with a vulnerable langgraph-sdk version. It passes config["configurable"]["threadid"] into threads.stream(...), and its dependency range permits affected SDK versions.
Impact
An application is affected only if it passes attacker-controlled text as a streaming threadid or assistantid. In that configuration, an attacker may select another readable path on the configured server and cause the SDK to return that response to the application. Through threadid, the attacker can also control the query string, for example by targeting /store/items?namespace=...&key=...; assistantid controls only the path. The affected requests are GET operations, so this issue does not provide a write primitive.
The LangGraph Platform is not exposed to this issue.
Remediation
Upgrade langgraph-sdk to version 0.4.6 or later. The fix encodes assistantid in gettree and threadid in fetchstate with quotepathparam in both synchronous and asynchronous stream modules.
If you use RemoteGraph, also upgrade langgraph to version 1.2.14 or later, which requires langgraph-sdk>=0.4.6.
Other sources
LangGraph Python SDK is used to connect to running LangGraph API servers, manage assistants, threads and stream runs from Python applications. From langgraph-sdk 0.4.0 until 0.4.6, and from langgraph 1.2.3 until 1.2.14 when RemoteGraph v3 streaming uses an affected langgraph-sdk version, the synchronous and asynchronous v3 stream gettree and fetchstate helpers interpolate caller-controlled assistantid and threadid values into authenticated GET request paths without using quotepathparam. Relative path segments can therefore be normalized into another readable path on the configured server while retaining authentication headers. This issue is fixed in langgraph-sdk 0.4.6 and langgraph 1.2.14.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
pip/langgraphto a version that resolves this vulnerability.Fixed in 1.2.14 - Upgrade
Upgrade
pip/langgraph-sdkto a version that resolves this vulnerability.Fixed in 0.4.6 - Upgrade
Upgrade
langgraph-sdkto a version that resolves this vulnerability.Fixed in 0.4.6 - Upgrade
Upgrade
langgraphto a version that resolves this vulnerability.Fixed in 1.2.14
Event History
Frequently Asked Questions
Which deployments are exposed?
Python applications using langgraph-sdk 0.4.0 through 0.4.6 are affected. Applications using langgraph 1.2.3 through 1.2.14 are affected when RemoteGraph v3 streaming uses an affected langgraph-sdk version.
What does an attacker need to exploit this?
An attacker needs the ability to supply assistant_id or thread_id values used by the synchronous or asynchronous v3 stream get_tree or _fetch_state helpers. The vulnerable request is authenticated, so normalized relative path segments can redirect the request to another readable path on the configured server while retaining authentication headers.
What should be done to remediate the issue?
Upgrade to langgraph-sdk 0.4.6 or later, and upgrade langgraph to 1.2.14 or later where applicable. If immediate upgrading is not possible, do not allow untrusted input to populate assistant_id or thread_id values passed to the affected helpers.