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CVE-2024-1455

Billion Laughs Attack leading to DoS in langchain-ai/langchain

5.9 MediumFix available

A vulnerability in the langchain-ai/langchain repository allows for a Billion Laughs Attack, a type of XML External Entity (XXE) exploitation. By nesting multiple layers of entities within an XML document, an attacker can cause the XML parser to consume excessive CPU and memory resources, leading to a denial of service (DoS).

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.76%Up 0.7 points since Mar 27, 2024
90%50%10%1%

What each source reports

CVE List Score used 5.9

Billion Laughs Attack leading to DoS in langchain-ai/langchain

A vulnerability in the langchain-ai/langchain repository allows for a Billion Laughs Attack, a type of XML External Entity (XXE) exploitation. By nesting multiple layers of entities within an XML document, an attacker can cause the XML parser to consume excessive CPU and memory resources, leading to a denial of service (DoS).

Record
CVE-2024-1455
CVSS 3.0
5.9 MediumCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-776
Updated
2026-11-02
EUVDEUVD-2024-0987 5.9

A vulnerability in the langchain-ai/langchain repository allows for a Billion Laughs Attack, a type of XML External Entity (XXE) exploitation. By nesting multiple layers of entities within an XML document, an attacker can cause the XML parser to consume excessive CPU and memory resources, leading to a denial of service (DoS).

Record
EUVD-2024-0987
CVSS 3.0
5.9 MediumCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-03
GitHub AdvisoriesGHSA-q84m-rmw3-4382 5.9

LangChain's XMLOutputParser vulnerable to XML Entity Expansion

The XMLOutputParser in LangChain uses the etree module from the XML parser in the standard python library which has some XML vulnerabilities; see: https://docs.python.org/3/library/xml.html

This primarily affects users that combine an LLM (or agent) with the XMLOutputParser and expose the component via an endpoint on a web-service.

This would allow a malicious party to attempt to manipulate the LLM to produce a malicious payload for the parser that would compromise the availability of the service.

A successful attack is predicated on:

  1. Usage of XMLOutputParser
  2. Passing of malicious input into the XMLOutputParser either directly or by trying to manipulate an LLM to do so on the users behalf
  3. Exposing the component via a web-service
Record
GHSA-q84m-rmw3-4382
CVSS 3.0
5.9 MediumCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-776
Updated
2026-11-02
NVD 5.9

A vulnerability in the langchain-ai/langchain repository allows for a Billion Laughs Attack, a type of XML External Entity (XXE) exploitation. By nesting multiple layers of entities within an XML document, an attacker can cause the XML parser to consume excessive CPU and memory resources, leading to a denial of service (DoS).

Record
CVE-2024-1455
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 3.0
5.9 MediumCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-776
Updated
2026-11-02
OSV 5.9

Billion Laughs Attack leading to DoS in langchain-ai/langchain

A vulnerability in the langchain-ai/langchain repository allows for a Billion Laughs Attack, a type of XML External Entity (XXE) exploitation. By nesting multiple layers of entities within an XML document, an attacker can cause the XML parser to consume excessive CPU and memory resources, leading to a denial of service (DoS).

Record
CVE-2024-1455
CVSS 3.0
5.9 MediumCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-776
Updated
2026-11-02
OSVGHSA-q84m-rmw3-4382 5.9

LangChain's XMLOutputParser vulnerable to XML Entity Expansion

The XMLOutputParser in LangChain uses the etree module from the XML parser in the standard python library which has some XML vulnerabilities; see: https://docs.python.org/3/library/xml.html

This primarily affects users that combine an LLM (or agent) with the XMLOutputParser and expose the component via an endpoint on a web-service.

This would allow a malicious party to attempt to manipulate the LLM to produce a malicious payload for the parser that would compromise the availability of the service.

A successful attack is predicated on:

  1. Usage of XMLOutputParser
  2. Passing of malicious input into the XMLOutputParser either directly or by trying to manipulate an LLM to do so on the users behalf
  3. Exposing the component via a web-service
Record
GHSA-q84m-rmw3-4382
CVSS 3.0
5.9 MediumCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-776
Updated
2026-11-02
OSVPYSEC-2026-1519 5.9

LangChain's XMLOutputParser vulnerable to XML Entity Expansion

The XMLOutputParser in LangChain uses the etree module from the XML parser in the standard python library which has some XML vulnerabilities; see: https://docs.python.org/3/library/xml.html

This primarily affects users that combine an LLM (or agent) with the XMLOutputParser and expose the component via an endpoint on a web-service.

This would allow a malicious party to attempt to manipulate the LLM to produce a malicious payload for the parser that would compromise the availability of the service.

A successful attack is predicated on:

  1. Usage of XMLOutputParser
  2. Passing of malicious input into the XMLOutputParser either directly or by trying to manipulate an LLM to do so on the users behalf
  3. Exposing the component via a web-service
Record
PYSEC-2026-1519
CVSS 3.0
5.9 MediumCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
langchain-core
PyPI
before 0.1.35
0.1.35
langchain-core
PyPI
before 0.1.35, plus listed versions
0.0.10.0.100.0.110.0.120.0.13
Show 45 moreShow less
0.0.13rc10.0.13rc20.0.20.0.30.0.40.0.50.0.60.0.70.0.80.0.90.1.00.1.10.1.100.1.110.1.120.1.12rc10.1.130.1.140.1.150.1.15rc10.1.15rc20.1.160.1.170.1.180.1.190.1.20.1.200.1.210.1.220.1.230.1.240.1.250.1.260.1.270.1.280.1.290.1.30.1.300.1.310.1.320.1.330.1.33rc10.1.340.1.40.1.5
0.1.35

History

History
RecordedChangedSources
aliases, publishedEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2024-1455 is a medium vulnerability (CVSS 5.9) in Langchain, published March 26, 2024. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.76%, the 55th percentile. Fixed in langchain-core 0.1.35.

References

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