Secret-length disclosure via early comparison return
Published Apr 7, 2024 · Updated Mar 13, 2025
Timing side channel in Mojolicious before 8.65 allows remote attackers to infer a secret string's length through response timing. The Mojo::Util secure_compare function returns immediately when the two input lengths differ, making response duration reveal whether a guessed length matches the secret. Only applications running versions after 1.74 that expose secret comparisons to attacker-controlled input are affected, and the disclosed consequence is limited to secret-length inference.
Summary
What happened
Timing side channel in Mojolicious before 8.65 allows remote attackers to infer a secret string's length through response timing. The Mojo::Util secure_compare function returns immediately when the two input lengths differ, making response duration reveal whether a guessed length matches the secret. Only applications running versions after 1.74 that expose secret comparisons to attacker-controlled input are affected, and the disclosed consequence is limited to secret-length inference.
The record
- CVE
- CVE-2020-36829
- Published
- Apr 7, 2024
- Updated
- Mar 13, 2025
- Vendor
- Mojolicious
- Product
- Mojolicious
- Classifications
- Unavailable
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 7, 2024CVE publishedPublication date reported by the CVE source.
- Mar 13, 2025Record 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 <8.65
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
No sourced classifications are available.
Public exploit references
- Upstream secure_compare timing benchmarkproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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