CVE-2026-50185 RustCrypto Cmov/CmovEq on aarch64 can produce wrong results if high-bits of registers are set
Incorrect constant-time conditional move results on aarch64 when high register bits are set, potentially compromising cryptographic operations.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-50185?
CVE-2026-50185 is a low-severity vulnerability in RustCrypto utils, published on 17 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
RustCrypto CMOV provides conditional move CPU intrinsics which are guaranteed on major platforms to execute in constant-time and not be rewritten as branches by the compiler. From 0.1.1 until 0.5.4, the aarch64 implementations of Cmov and CmovEq in cmov/src/backends/aarch64.rs assume high bits are zero-extended when loading values smaller than a register, so set high bits such as [8..] in a Cmov selector or [16..] of self or other in the u16 and i16 CmovEq implementations can cause left.cmovz(&right, condition) to produce incorrect output. This issue is fixed in version 0.5.4.
Weakness: CWE-758
Which versions are affected by CVE-2026-50185?
2 open source packages ship an affected version, including cmov. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
cmov crates.io | From 0.1.1 | 0.5.4 |
cmov crates.io | From 0.1.1 | 0.5.4 |
Products include Rustcrypto Cmov.
How do I fix CVE-2026-50185?
Upgrade cmov to 0.5.4 or later.
Is CVE-2026-50185 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-50185 exists.
Other vulnerabilities in RustCrypto utils
Sources
Also known as DEBIAN-CVE-2026-50185, GHSA-3rjw-m598-pq24, MINI-34p9-47x3-qf43, MINI-49rx-4h39-xpp8, MINI-gpf4-rjwv-74h6, MINI-h46m-v8xj-9m66 and 3 more.