CVE-2026-120420

drools-drl-parser: uncontrolled recursion when parsing deeply nested parenthesised expressions leads to denial of service (StackOverflowError)

Published n/a CVSS 3.1 · 5.3 Medium EPSS n/a KEV · Not listed
Description
A denial-of-service vulnerability was found in the Drools DRL expression parser (org.drools:drools-drl-parser). The ANTLR4-generated DRL expression grammar parses parenthesised sub-expressions through mutually recursive descent rules with no limit on nesting depth. When a deeply nested parenthesised constraint expression (approximately 300-400 levels) is parsed, the parsing thread exhausts its stack and a java.lang.StackOverflowError is raised and propagates out of the parse call instead of being converted into a DroolsParserException. An actor able to supply a crafted DRL expression to an application that parses untrusted DRL can cause a denial of service.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

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History
Type Values Removed Values Added
Description A denial-of-service vulnerability was found in the Drools DRL expression parser (org.drools:drools-drl-parser). The ANTLR4-generated DRL expression grammar parses parenthesised sub-expressions through mutually recursive descent rules with no limit on nesting depth. When a deeply nested parenthesised constraint expression (approximately 300-400 levels) is parsed, the parsing thread exhausts its stack and a java.lang.StackOverflowError is raised and propagates out of the parse call instead of being converted into a DroolsParserException. An actor able to supply a crafted DRL expression to an application that parses untrusted DRL can cause a denial of service.
Title drools-drl-parser: uncontrolled recursion when parsing deeply nested parenthesised expressions leads to denial of service (StackOverflowError)
Weaknesses CWE-674
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'}

threat_severity

Moderate

Subscriptions

No data.

Weaknesses

Sources