Server overload via cubic regex backtracking
Published Feb 20, 2020 · Updated Aug 4, 2024
Regular expression denial of service in ua-parser uap-core before 0.7.3 allows remote attackers to overload servers via crafted User-Agent strings. Overlapping quantifiers and capture groups in four device-parser regexes trigger approximately cubic backtracking on long nonmatching inputs. Exploitation requires a consuming implementation to evaluate an affected regex against a malicious header; sustained CPU consumption can interrupt service.
Summary
What happened
Regular expression denial of service in ua-parser uap-core before 0.7.3 allows remote attackers to overload servers via crafted User-Agent strings. Overlapping quantifiers and capture groups in four device-parser regexes trigger approximately cubic backtracking on long nonmatching inputs. Exploitation requires a consuming implementation to evaluate an affected regex against a malicious header; sustained CPU consumption can interrupt service.
The record
- CVE
- CVE-2020-5243
- Published
- Feb 20, 2020
- Updated
- Aug 4, 2024
- Vendor
- ua-parser
- Product
- uap-core
- Classifications
- CWE-20, T1499.004
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Feb 20, 2020CVE publishedPublication date reported by the CVE source.
- Aug 4, 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=< 0.7.3
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
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
- Upstream crafted User-Agent proof-of-concept stringsproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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