Processing interruption via catastrophic blockquote regex backtracking
Published Dec 20, 2021 · Updated Aug 4, 2024
Regular expression denial of service in jsx-slack before 4.5.2 allows remote attackers to interrupt processing via crafted JSX. The blockquote escape replacer in src/mrkdwn/escape.ts applies nested, overly broad tag-matching expressions to repeated JSX tags containing multibyte characters, causing catastrophic backtracking. Exploitation requires a consuming application to render attacker-controlled blockquote content; CPU exhaustion can delay or halt that process without disclosing or modifying data.
Summary
What happened
Regular expression denial of service in jsx-slack before 4.5.2 allows remote attackers to interrupt processing via crafted JSX. The blockquote escape replacer in src/mrkdwn/escape.ts applies nested, overly broad tag-matching expressions to repeated JSX tags containing multibyte characters, causing catastrophic backtracking. Exploitation requires a consuming application to render attacker-controlled blockquote content; CPU exhaustion can delay or halt that process without disclosing or modifying data.
The record
- CVE
- CVE-2021-43843
- Published
- Dec 20, 2021
- Updated
- Aug 4, 2024
- Vendor
- Yuki Hattori
- Product
- jsx-slack
- Classifications
- CWE-400, CWE-1333, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Dec 20, 2021CVE 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
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 4.5.2
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
- Maintainer blockquote ReDoS demonstrationproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo