CVE-2026-44843
Description
A flaw was found in LangChain, a framework for building agents and large language model (LLM)-powered applications. Older runtime code paths within LangChain deserialize application-controlled payloads using overly broad object allowlists. A remote attacker can exploit this by supplying specially crafted LangChain serialized constructor dictionaries, leading to the instantiation of classes with untrusted arguments. This can result in the disclosure of sensitive information and potential partial compromise of data integrity.
Statement
This Important vulnerability in LangChain allows a remote attacker to achieve information disclosure and partial data integrity compromise. The flaw arises from overly broad object allowlists in older runtime code paths, which can deserialize attacker-controlled payloads and instantiate classes with untrusted arguments. Red Hat products integrating LangChain are affected if they process untrusted structured input and utilize deprecated APIs such as RunnableWithMessageHistory, astream_log(), or astream_events(version="v1"), potentially leading to prompt injection or sensitive data exposure.
Mitigation
To mitigate this issue, applications using LangChain should avoid passing untrusted structured input directly to load() or loads() functions. Instead, ensure all incoming untrusted data is validated and canonicalized into an inert schema before being processed by LangChain. Additionally, migrate away from deprecated LangChain APIs, including RunnableWithMessageHistory, astream_log(), and astream_events(version="v1"), as these older code paths are more susceptible to insecure deserialization.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.2 | N/A | 8.2 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | Low | N/A | Low |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Application Data; Unexpected State
Attackers can modify unexpected objects or data that was assumed to be safe from modification. Deserialized data or code could be modified without using the provided accessor functions, or unexpected functions could be invoked.
Availability
Technical Impact: DoS: Resource Consumption (CPU)
If a function is making an assumption on when to terminate, based on a sentry in a string, it could easily never terminate.
Other
Technical Impact: Varies by Context
The consequences can vary widely, because it depends on which objects or methods are being deserialized, and how they are used. Making an assumption that the code in the deserialized object is valid is dangerous and can enable exploitation. One example is attackers using gadget chains to perform unauthorized actions, such as generating a shell.
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