Vulnerability · Published Jul 17, 2026 · Assigned by GitHub_M
CVE-2026-50185RustCrypto Cmov/CmovEq on aarch64 can produce wrong results if high-bits of registers are set
Low 2.0
In plain English
A low-severity security flaw in utils from RustCrypto. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 5% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:14 | rust-cmov | 0.5.4-1 | DEBIAN-CVE-2026-50185 |
| Ubuntu:26.10 | rust-cmov | no fix listed | UBUNTU-CVE-2026-50185 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| RustCrypto | utils | >= 0.1.1, < 0.5.4 |
Weakness: CWE-758 · Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N