Timing Oracle in RSA Decryption

Summary

A timing based side channel exists in the OpenSSL RSA Decryption implementation which could be sufficient to recover a plaintext across a network in a Bleichenbacher style attack. To achieve a successful decryption an attacker would have to be able to send a very large number of trial messages for decryption. The vulnerability affects all RSA padding modes: PKCS#1 v1.5, RSA-OEAP and RSASVE. For example, in a TLS connection, RSA is commonly used by a client to send an encrypted pre-master secret to the server. An attacker that had observed a genuine connection between a client and a server could use this flaw to send trial messages to the server and record the time taken to process them. After a sufficiently large number of messages the attacker could recover the pre-master secret used for the original connection and thus be able to decrypt the application data sent over that connection.

Timeline

1. Feb 8, 2023, 7:04 PM UTCCVE published
2. Mar 6, 2025, 3:57 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Oct 14, 2026, 2:17 PM UTCRecord last updated
4. Oct 22, 2026EPSS reached 10%

   FIRST estimates at least a 10% chance of exploitation in the next 30 days

Affected versions

• OpenSSL OpenSSL

  From 3.0.0 · fixed in 3.0.8; From 1.1.1 · fixed in 1.1.1t; From 1.0.2 · fixed in 1.0.2zg

• openssl-srccrates.io

  fixed in 111.25.0

• openssl-srccrates.io

  From 300.0.0 · fixed in 300.0.12

• openssl-srccrates.io

  From 0.0.0-0 · fixed in 111.25.0; From 300.0.0 · fixed in 300.0.12

References 2