TLS session decryption via DHE timing oracle
Published Feb 16, 2023 · Updated Mar 19, 2025
Timing side channel in Mozilla Firefox before 78 and Firefox ESR before 68.10 allows remote attackers to decrypt DHE TLS sessions. TLS 1.2 and earlier strip leading zero bytes from the Diffie-Hellman premaster secret, making key-derivation timing reveal whether the secret begins with zero. Exploitation requires observation of a victim handshake, precise timing near a server that reuses DH keys, and many crafted handshakes; it exposes only the targeted session.
Summary
What happened
Timing side channel in Mozilla Firefox before 78 and Firefox ESR before 68.10 allows remote attackers to decrypt DHE TLS sessions. TLS 1.2 and earlier strip leading zero bytes from the Diffie-Hellman premaster secret, making key-derivation timing reveal whether the secret begins with zero. Exploitation requires observation of a victim handshake, precise timing near a server that reuses DH keys, and many crafted handshakes; it exposes only the targeted session.
The record
- CVE
- CVE-2020-12413
- Published
- Feb 16, 2023
- Updated
- Mar 19, 2025
- Vendor
- Mozilla
- Product
- Firefox
- Classifications
- CWE-203, T1557
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 16, 2023CVE publishedPublication date reported by the CVE source.
- Mar 19, 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=unspecified <78
What conditions does exploitation require?
What is affected?
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.
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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