vodozemac has degraded secret zeroization capabilities

Versions 0.5.0 and 0.5.1 of vodozemac have degraded secret zeroization capabilities, due to changes in third-party cryptographic dependencies (the Dalek crates), which moved secret zeroization capabilities behind a feature flag while vodozemac disabled the default feature set.

Impact

The degraded zeroization capabilities could result in the production of more memory copies of encryption secrets and secrets could linger in memory longer than necessary. This marginally increases the risk of sensitive data exposure.

Overall, we consider the impact of this issue to be low. Although cryptographic best practices recommend the clearing of sensitive information from memory once it's no longer needed, the inherent limitations of Rust regarding absolute zeroization reduce the practical severity of this lapse.

Patches

The patch is in commit https://github.com/matrix-org/vodozemac/pull/130/commits/297548cad4016ce448c4b5007c54db7ee39489d9.

Workarounds

None.

For more information

If you have any questions or comments about this advisory please email us at security at matrix.org.