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PYSEC-2026-1532

HighCVSS 7.8 / 10
Published Jul 7, 2026·Last modified Jul 7, 2026
Affected Components(0)

No affected components available

Description

Summary

A LLM application leveraging XMLToolMessage class may be exposed to untrusted XML input that could result in DoS and/or exposing local files with sensitive information.

Details

XMLToolMessage uses lxml without safeguards: https://github.com/langroid/langroid/blob/df6227e6c079ec22bb2768498423148d6685acff/langroid/agent/xml_tool_message.py#L51-L52 lxml is vulnerable to quadratic blowup attacks and processes external entity declarations for local files by default. Check here: https://pypi.org/project/defusedxml/#python-xml-libraries

PoC

A typical Quadratic blowup XML payload looks like this:

<!DOCTYPE bomb [
<!ENTITY a "aaaaaaaaaa">
<!ENTITY b "&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;">
<!ENTITY c "&b;&b;&b;&b;&b;&b;&b;&b;&b;&b;">
]>
<bomb>&c;</bomb>

Here, &a; expands to 10 characters, &b; expands to 100, and &c; expands to 1000, causing exponential memory usage and potentially crashing the application.

Fix

Langroid 0.53.4 initializes XMLParser with flags to prevent XML External Entity (XXE), billion laughs, and external DTD attacks by disabling entity resolution, DTD loading, and network access. https://github.com/langroid/langroid/commit/36e7e7db4dd1636de225c2c66c84052b1e9ac3c3

Risk Scores
Base Score
7.8

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability.

Threat Intelligence
6.8

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.55%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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High severity
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