RUSTSEC-2026-0212
Potentially Incorrect Output of Constant-Time Swap/Select on Aarch64
The implementation of constant-time swap and select on aarch64
platforms used a cmp instruction in inline assembly to check whether
an 8-bit wide selector was 0. The cmp instruction works on 32-bit
registers, which included the unspecified high 24 bits of the cmp operand.
Depending on the execution environment the cmp
could thus potentially return an incorrect result because its
operand's high bits in the inline assembly were set when Rust expected them to be unset.
This could lead to incorrect results for the constant-time swap and select
operations built from this comparison.
Impact
In certain circumstances the swap and select instructions on aarch64 platforms returned incorrect results.
Mitigation
Starting from version 0.0.6, the selector is compared using a tst
instruction with a mask, which only compares the first 8 bits of the
selector.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
What each source reports
OSV Score used
Potentially Incorrect Output of Constant-Time Swap/Select on Aarch64
The implementation of constant-time swap and select on aarch64
platforms used a cmp instruction in inline assembly to check whether
an 8-bit wide selector was 0. The cmp instruction works on 32-bit
registers, which included the unspecified high 24 bits of the cmp operand.
Depending on the execution environment the cmp
could thus potentially return an incorrect result because its
operand's high bits in the inline assembly were set when Rust expected them to be unset.
This could lead to incorrect results for the constant-time swap and select
operations built from this comparison.
Impact
In certain circumstances the swap and select instructions on aarch64 platforms returned incorrect results.
Mitigation
Starting from version 0.0.6, the selector is compared using a tst
instruction with a mask, which only compares the first 8 bits of the
selector.
- Record
RUSTSEC-2026-0212- CVSS 4.0
- 8.2 High
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N - Updated
- 2026-11-02
Affected packages
| Package | Affected | Fixed |
|---|---|---|
libcrux-secretscrates.io |
0.0.0-0 up to 0.0.6 | 0.0.6 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
RUSTSEC-2026-0212 is a high vulnerability (CVSS 8.2) in libcrux-secrets, published May 26, 2026. No source lists public exploit code. Fixed in libcrux-secrets 0.0.6.