{"schemaVersion":3,"id":"CVE-2026-27794","aliases":["GHSA-mhr3-j7m5-c7c9","PYSEC-2026-2574"],"status":"published","duplicateOf":null,"title":null,"description":"LangGraph Checkpoint defines the base interface for LangGraph checkpointers. Prior to version 4.0.0, a Remote Code Execution vulnerability exists in LangGraph's caching layer when applications enable cache backends that inherit from `BaseCache` and opt nodes into caching via `CachePolicy`. Prior to `langgraph-checkpoint` 4.0.0, `BaseCache` defaults to `JsonPlusSerializer(pickle_fallback=True)`. When msgpack serialization fails, cached values can be deserialized via `pickle.loads(...)`. Caching is not enabled by default. Applications are affected only when the application explicitly enables a cache backend (for example by passing `cache=...` to `StateGraph.compile(...)` or otherwise configuring a `BaseCache` implementation), one or more nodes opt into caching via `CachePolicy`, and the attacker can write to the cache backend (for example a network-accessible Redis instance with weak/no auth, shared cache infrastructure reachable by other tenants/services, or a writable SQLite cache file). An attacker must be able to write attacker-controlled bytes into the cache backend such that the LangGraph process later reads and deserializes them. This typically requires write access to a networked cache (for example a network-accessible Redis instance with weak/no auth or shared cache infrastructure reachable by other tenants/services) or write access to local cache storage (for example a writable SQLite cache file via permissive file permissions or a shared writable volume). Because exploitation requires write access to the cache storage layer, this is a post-compromise / post-access escalation vector. LangGraph Checkpoint 4.0.0 patches the issue.","dates":{"published":"2026-02-25T16:53:47.176Z","modified":"2026-02-25T21:00:24.430Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":6.6,"severity":"medium","version":"3.1","versionLabel":"v3.1","source":"CVE.org","vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":6.6,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"OSV · 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