langchain-ai LangChain up to 0.3.1 output_parser.py MRKLOutputparser.parse redos

Summaryinfo

A vulnerability classified as problematic has been found in langchain-ai LangChain up to 0.3.1. This affects the function MRKLOutputparser.parse in the library libs/LangChain/LangChain/agents/mrkl/output_parser.py. The manipulation leads to redos. This vulnerability is referenced as CVE-2024-58340. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in langchain-ai LangChain up to 0.3.1. This issue affects the function MRKLOutputparser.parse in the library libs/LangChain/LangChain/agents/mrkl/output_parser.py. The manipulation with an unknown input leads to a redos vulnerability. Using CWE to declare the problem leads to CWE-1333. The product uses a regular expression with an inefficient, possibly exponential worst-case computational complexity that consumes excessive CPU cycles. Impacted is availability. The summary by CVE is:

LangChain versions up to and including 0.3.1 contain a regular expression denial-of-service (ReDoS) vulnerability in the MRKLOutputParser.parse() method (libs/langchain/langchain/agents/mrkl/output_parser.py). The parser applies a backtracking-prone regular expression when extracting tool actions from model output. An attacker who can supply or influence the parsed text (for example via prompt injection in downstream applications that pass LLM output directly into MRKLOutputParser.parse()) can trigger excessive CPU consumption by providing a crafted payload, causing significant parsing delays and a denial-of-service condition.

The weakness was published by LifeTeam2024. It is possible to read the advisory at huntr.com. The identification of this vulnerability is CVE-2024-58340 since 01/09/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1449.003 according to MITRE ATT&CK.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-2399). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

• Artificial Intelligence Software

Vendor

• langchain-ai

Name

• LangChain

Version

• 0.3.0
• 0.3.1

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Be aware that VulDB is the high quality source for vulnerability data.

Discussion