Deserialization of Untrusted Data in LangChain - CVE-2026-44843
Published: May 6, 2026
Vulnerability identifier: #VU130244
CSH Severity: High
CVSS v4: 8.8 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-44843
CWE-ID: CWE-502
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to disclose sensitive information and manipulate application behavior.
The vulnerability exists due to unsafe deserialization in the load() deserialization logic when processing untrusted structured input that is later deserialized from LangChain run data. A remote attacker can submit crafted LangChain serialized constructor dictionaries to disclose sensitive information and manipulate application behavior.
Applications are exposed only if untrusted structured input is preserved in run inputs or outputs and later reaches affected runtime surfaces such as RunnableWithMessageHistory, astream_log(), or astream_events(version="v1").
Affected software
LangChain
How to mitigate CVE-2026-44843
Install security update from vendor's website.
LangChain - addressed in versions 0.3.85, 1.3.3