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RUSTSEC-2023-0071

Marvin Attack: potential key recovery through timing sidechannels

Reported
Issued
Package
rsa (crates.io)
Type
Vulnerability
Categories
Keywords
#cryptography
Aliases
References
CVSS Score
5.9 MEDIUM
CVSS Details
Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality Impact
High
Integrity Impact
None
Availability Impact
None
CVSS Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Patched
no patched versions

Description

Impact

Due to a non-constant-time implementation, information about the private key is leaked through timing information which is observable over the network. An attacker may be able to use that information to recover the key.

Patches

No patch is yet available. The crypto-bigint migration (RustCrypto/RSA#394) did not close this. Tracking is RustCrypto/RSA#626 (padding still not constant-time). Implicit rejection work is in RustCrypto/RSA#680; default-path blinding is in RustCrypto/RSA#702.

Still affected as of 2026-09-12: rsa 0.9.10 (latest stable) and rsa 0.10.0-rc.18 (latest). patched = [] is intentional.

Workarounds

Avoid using the rsa crate in settings where attackers can observe timing, for example over the network. Local use on a non-compromised computer is fine.

References

This vulnerability was discovered as part of the "Marvin Attack", which revealed several implementations of RSA including OpenSSL had not properly mitigated timing sidechannel attacks.

Advisory available under CC0-1.0 license.