CVE-2026-23519 json
RustCrypto cmov: thumbv6m-none-eabi compiler emits non-constant time assembly when using cmovnz
published 2026-01-14 9 mo ago modified 2026-10-23 17 d ago also EUVD-2026-2731 , GHSA-2gqc-6j2q-83qp , RUSTSEC-2026-0003
- cvss
- 9.8
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.6%
- EPSS 0.6% chance of exploitation in 30 days, percentile 46%
- public exploits
- 0
- none known
Summary
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. Prior to 0.4.4, the thumbv6m-none-eabi (Cortex M0, M0+ and M1) compiler emits non-constant time assembly when using cmovnz (portable version). This vulnerability is fixed in 0.4.4.
Patch / fix
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- partial
- Assessed
- 9 mo ago
Exploit prediction
0.56% chance of exploitation in the next 30 days, higher than 46% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/RustCrypto/utils/security/advisories/GHSA-2gqc-6j2q-83qp referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 8.9 | CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N |
| CNA | 4.0 | 8.9 | CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
| NVD | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| crates.io | cmov | <0.4.4 >=0.0.0-0, <0.4.4 |
0.4.4 |
Affected products
- RustCrypto utils
Classification
References
-
github.com
/RustCrypto/utils/commit/55977257e7c82a309d5e8abfdd380a774f0f9778
web, patch
-
github.com
/RustCrypto/utils/security/advisories/GHSA-2gqc-6j2q-83qp
exploit, web, vendor-advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-23519
advisory
-
github.com
/RustCrypto/utils
package
-
rustsec.org
/advisories/RUSTSEC-2026-0003.html
web, advisory
-
crates.io
/crates/cmov
package
Sources
- CVE List CVE-2026-23519
- GitHub Advisory GHSA-2gqc-6j2q-83qp
- NVD CVE-2026-23519
- OSV RUSTSEC-2026-0003
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.