Service interruption via quadratic RFC2822 backtracking
Published Mar 31, 2023 · Updated Nov 4, 2025
ReDoS in Ruby Time 0.1.0 and 0.2.1 and Ruby 2.7.7 and earlier allows remote attackers to exhaust CPU with crafted time strings. Time.rfc2822 applies an ambiguous whitespace-and-optional-seconds regular expression to invalid input, causing quadratic backtracking before rejection. Exposure requires an application to pass attacker-controlled strings to the parser, where repeated inputs can delay processing and interrupt service.
Summary
What happened
ReDoS in Ruby Time 0.1.0 and 0.2.1 and Ruby 2.7.7 and earlier allows remote attackers to exhaust CPU with crafted time strings. Time.rfc2822 applies an ambiguous whitespace-and-optional-seconds regular expression to invalid input, causing quadratic backtracking before rejection. Exposure requires an application to pass attacker-controlled strings to the parser, where repeated inputs can delay processing and interrupt service.
The record
- CVE
- CVE-2023-28756
- Published
- Mar 31, 2023
- Updated
- Nov 4, 2025
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-1333, T1499.003
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 31, 2023CVE publishedPublication date reported by the CVE source.
- Nov 4, 2025Record updatedLatest update available in the CVE record.
Exploitability
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What is affected?
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Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
- ruby/time RFC2822 nonlinear regression testproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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