RSA ciphertext decryption via TLS timing oracle
Published Feb 5, 2024 · Updated Mar 16, 2026
Observable timing discrepancies in cryptlib 3.4.7 allow remote attackers to decrypt RSA ciphertexts through repeated TLS connections. The RSA key-exchange path performs distinguishable PKCS#1 v1.5 decryption processing when USE_RSA_SUITES is enabled, exposing a timing oracle. Exploitation requires a custom or test build with the undocumented define and enough requests to measure timing; the maintainer disputes exposure in unmodified builds.
Summary
What happened
Observable timing discrepancies in cryptlib 3.4.7 allow remote attackers to decrypt RSA ciphertexts through repeated TLS connections. The RSA key-exchange path performs distinguishable PKCS#1 v1.5 decryption processing when USE_RSA_SUITES is enabled, exposing a timing oracle. Exploitation requires a custom or test build with the undocumented define and enough requests to measure timing; the maintainer disputes exposure in unmodified builds.
The record
- CVE
- CVE-2024-0202
- Published
- Feb 5, 2024
- Updated
- Mar 16, 2026
- Vendor
- Digital Data Security Limited
- Product
- cryptlib
- Classifications
- CWE-208
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 5, 2024CVE publishedPublication date reported by the CVE source.
- Mar 16, 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=3.4.7
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
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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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