Application hang via boolean-casting regex backtracking
Published Dec 18, 2022 · Updated Aug 3, 2024
Regular-expression denial of service in ActiveAttr 0.15.0 through 0.15.2 allows attackers to hang a calling Ruby application via a crafted value. BooleanTypecaster#call matches the value against alternatives containing overlapping zero quantifiers, causing excessive backtracking on a long zero string followed by a nonmatching character. Exploitation requires a consuming application to pass attacker-controlled input to the Boolean typecaster, stalling the thread that evaluates the expression.
Summary
What happened
Regular-expression denial of service in ActiveAttr 0.15.0 through 0.15.2 allows attackers to hang a calling Ruby application via a crafted value. BooleanTypecaster#call matches the value against alternatives containing overlapping zero quantifiers, causing excessive backtracking on a long zero string followed by a nonmatching character. Exploitation requires a consuming application to pass attacker-controlled input to the Boolean typecaster, stalling the thread that evaluates the expression.
The record
- CVE
- CVE-2021-4250
- Published
- Dec 18, 2022
- Updated
- Aug 3, 2024
- Vendor
- Chris Griego
- Product
- ActiveAttr
- Classifications
- CWE-404, T1499.003
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Dec 18, 2022CVE publishedPublication date reported by the CVE source.
- Aug 3, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0.15.0
- Affected versionversion=0.15.1
- Affected versionversion=0.15.2
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Long zero-string ReDoS proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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