Code execution via BaseCache pickle fallback
Published Feb 25, 2026 · Updated Feb 25, 2026
Unsafe deserialization in LangChain LangGraph Checkpoint before 4.0.0 allows attackers with cache write access to execute code. BaseCache configures JsonPlusSerializer with pickle fallback enabled, so loads_typed passes attacker-controlled cached bytes to pickle.loads when msgpack decoding fails. Caching and CachePolicy are disabled by default; exploitation requires opted-in caching plus writable Redis or local cache storage and runs code in the LangGraph process.
Summary
What happened
Unsafe deserialization in LangChain LangGraph Checkpoint before 4.0.0 allows attackers with cache write access to execute code. BaseCache configures JsonPlusSerializer with pickle fallback enabled, so loads_typed passes attacker-controlled cached bytes to pickle.loads when msgpack decoding fails. Caching and CachePolicy are disabled by default; exploitation requires opted-in caching plus writable Redis or local cache storage and runs code in the LangGraph process.
The record
- CVE
- CVE-2026-27794
- Published
- Feb 25, 2026
- Updated
- Feb 25, 2026
- Vendor
- LangChain
- Product
- LangGraph Checkpoint
- Classifications
- CWE-502
- Attack vector
- network
- Privileges
- admin
Timeline
How it unfolded
- Feb 25, 2026CVE publishedPublication date reported by the CVE source.
- Feb 25, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=< 4.0.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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