DescriptionA 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.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDLA-3325-1, DSA-5343-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
openssl (PTS)jessie, jessie (lts)1.0.1t-1+deb8u21vulnerable
stretch (security)1.1.0l-1~deb9u6vulnerable
stretch (lts), stretch1.1.0l-1~deb9u9fixed
buster (security)1.1.1n-0+deb10u6fixed
bullseye (security)1.1.1n-0+deb11u5fixed
bookworm (security), bookworm3.0.11-1~deb12u2fixed
openssl1.0 (PTS)stretch (security)1.0.2u-1~deb9u7vulnerable
stretch (lts), stretch1.0.2u-1~deb9u9vulnerable

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs

Notes;a=commit;h=8e257b86e5812c6e1cfa9e8e5f5660ac7bed899d (openssl-3.0.8) (reverted in 908eaceb62624f5b5c505b286d904bd3a4e8a64a);a=commit;h=a00d757d9ca212994625d1a02c81cc5edd27e13b (openssl-3.0.9);a=commit;h=43d8f88511991533f53680a751e9326999a6a31f (OpenSSL_1_1_1t) (reverted in 0372649a943fb23f7f08c7acdbc01464b9df03f0);a=commit;h=3f499b24f3bcd66db022074f7e8b4f6ee266a3ae (OpenSSL_1_1_1t);a=commit;h=8daa2616bbe6f7994e0cdd796d3280118c51d8d8 (OpenSSL_1_1_1t)
[jessie] - openssl <ignored> (Too intrusive to backport)
[stretch] - openssl1.0 <ignored> (Too intrusive to backport)
rsa_ossl.c was called rsa_eay.c in jessie

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