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Unaligned memory access in rand_core

Critical severity GitHub Reviewed Published Aug 1, 2020 in rust-random/rand • Updated Jan 9, 2023

Package

cargo rand_core (Rust)

Affected versions

>= 0.4.0, < 0.4.2
< 0.3.1

Patched versions

0.4.2
0.3.1

Description

Impact

Affected versions of this crate violated alignment when casting byte slices to integer slices, resulting in undefined behavior. rand_core::BlockRng::next_u64 and rand_core::BlockRng::fill_bytes are affected.

Patches

The flaw was corrected by Ralf Jung and Diggory Hardy for rand_core >= 0.4.2.

Workarounds

None.

References

See Rand's changelog.

For more information

If you have any questions or comments about this advisory, open an issue in the Rand repository.

References

@vks vks published to rust-random/rand Aug 1, 2020
Reviewed Aug 18, 2021
Published to the GitHub Advisory Database Aug 25, 2021
Last updated Jan 9, 2023

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS score

0.222%
(61st percentile)

Weaknesses

CVE ID

CVE-2020-25576

GHSA ID

GHSA-mmc9-pwm7-qj5w

Source code

Credits

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