CPU exhaustion via repeated response-buffer rescanning
Published May 9, 2026 · Updated May 9, 2026
Denial of service in Ruby net-imap before 0.4.24, 0.5.0 through 0.5.13, and 0.6.0 through 0.6.3 allows remote attackers to exhaust CPU. ResponseReader rescans the entire growing response buffer for each literal even though its regular expression needs only the final 23 bytes, producing quadratic work. Exploitation requires a client to connect to a hostile or compromised IMAP server, and the bounded consequence is CPU exhaustion that interrupts the client application.
Summary
What happened
Denial of service in Ruby net-imap before 0.4.24, 0.5.0 through 0.5.13, and 0.6.0 through 0.6.3 allows remote attackers to exhaust CPU. ResponseReader rescans the entire growing response buffer for each literal even though its regular expression needs only the final 23 bytes, producing quadratic work. Exploitation requires a client to connect to a hostile or compromised IMAP server, and the bounded consequence is CPU exhaustion that interrupts the client application.
The record
- CVE
- CVE-2026-42245
- Published
- May 9, 2026
- Updated
- May 9, 2026
- Vendor
- libwww-perl
- Product
- net-imap
- Classifications
- CWE-407, T1499.003
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 9, 2026CVE publishedPublication date reported by the CVE source.
- May 9, 2026Record 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=< 0.4.24
- Affected versionversion=>= 0.5.0, < 0.5.14
- Affected versionversion=>= 0.6.0, < 0.6.4
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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