Application hang via email regex backtracking
Published Mar 19, 2021 · Updated Aug 3, 2024
Regular expression denial of service in Schema-Inspector before 2.0.0 allows remote attackers to hang applications via crafted email input. The built-in email validator applies an ambiguous expression whose overlapping alternatives trigger exponential backtracking on long dotted addresses. Exposure requires a consuming application or browser page to pass attacker-controlled strings to the email pattern; other validation modes are unaffected, while a match can monopolize execution and freeze the process or page.
Summary
What happened
Regular expression denial of service in Schema-Inspector before 2.0.0 allows remote attackers to hang applications via crafted email input. The built-in email validator applies an ambiguous expression whose overlapping alternatives trigger exponential backtracking on long dotted addresses. Exposure requires a consuming application or browser page to pass attacker-controlled strings to the email pattern; other validation modes are unaffected, while a match can monopolize execution and freeze the process or page.
The record
- CVE
- CVE-2021-21267
- Published
- Mar 19, 2021
- Updated
- Aug 3, 2024
- Vendor
- Schema-Inspector
- Product
- Schema-Inspector
- Classifications
- CWE-20, CWE-400, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 19, 2021CVE 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=< 2.0.0
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
- GHSL-2020-358 proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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