Service interruption via catastrophic regex backtracking
Published Aug 18, 2021 · Updated Sep 16, 2024
Regular expression denial of service in Steve Mao trim-off-newlines before 1.0.3 allows attackers to interrupt services via crafted strings. The exported function applies an end-anchored newline-matching expression across untrusted strings, triggering disproportionate backtracking on repeated CRLF sequences. Reachability depends on a consuming Node.js application passing attacker-controlled text to the library; exploitation consumes CPU and interrupts that application's service.
Summary
What happened
Regular expression denial of service in Steve Mao trim-off-newlines before 1.0.3 allows attackers to interrupt services via crafted strings. The exported function applies an end-anchored newline-matching expression across untrusted strings, triggering disproportionate backtracking on repeated CRLF sequences. Reachability depends on a consuming Node.js application passing attacker-controlled text to the library; exploitation consumes CPU and interrupts that application's service.
The record
- CVE
- CVE-2021-23425
- Published
- Aug 18, 2021
- Updated
- Sep 16, 2024
- Vendor
- Steve Mao
- Product
- trim-off-newlines
- Classifications
- CWE-400, T1499
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 18, 2021CVE publishedPublication date reported by the CVE source.
- Sep 16, 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?
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- Affected versionversion=0 <unspecified
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.
Public exploit references
- Crafted CRLF sequence proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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