Code execution via permissive msgpack object reconstruction
Published Mar 5, 2026 · Updated Mar 5, 2026
Deserialization of untrusted data in LangGraph 1.0.9 and earlier allows attackers to execute code through crafted persisted checkpoints. JsonPlusSerializer permits all msgpack extension types by default and reconstructs named Python types instead of enforcing the strict built-in allowlist. Exploitation requires privileged write access to checkpoint bytes and a later load or resume, escalating a compromised backing store into code execution in the application runtime.
Summary
What happened
Deserialization of untrusted data in LangGraph 1.0.9 and earlier allows attackers to execute code through crafted persisted checkpoints. JsonPlusSerializer permits all msgpack extension types by default and reconstructs named Python types instead of enforcing the strict built-in allowlist. Exploitation requires privileged write access to checkpoint bytes and a later load or resume, escalating a compromised backing store into code execution in the application runtime.
The record
- CVE
- CVE-2026-28277
- Published
- Mar 5, 2026
- Updated
- Mar 5, 2026
- Vendor
- LangChain
- Product
- LangGraph
- Classifications
- CWE-502
- Attack vector
- adjacent
- Privileges
- admin
Timeline
How it unfolded
- Mar 5, 2026CVE publishedPublication date reported by the CVE source.
- Mar 5, 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=<= 1.0.9
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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