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CVE-2026-23519

34
FAUCET Score

CVE-2026-23519 is a critical vulnerability affecting RustCrypto CMOV versions prior to 0.4.4, specifically impacting the thumbv6m-none-eabi compiler. This flaw causes the cmovnz intrinsic to generate non-constant time assembly, which can lead to timing side-channel attacks. With a CVSS score of 9.8 (CRITICAL), it presents a high risk due to its network-based attack vector, low attack complexity, and potential for complete compromise of confidentiality, integrity, and availability. While there is no evidence of active exploitation or public exploit code (Metasploit, Nuclei, ExploitDB), the vulnerability has garnered significant community discussion with 10 mentions, indicating awareness among security researchers.

Impacted Technologies

VendorProductVersion(s)CPE
< 0.4.4CPE matchmatch criteria
cpe:2.3:a:rustcrypto:cmov:*:*:*:*:*:rust:*:*

CVSS Data

CVSS version used by this source: 4.0

8.9HIGH

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

Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
VS Confidentiality
HIGH
VS Integrity
NONE
VS Availability
NONE
SS Confidentiality
HIGH
SS Integrity
NONE
SS Availability
NONE
Exploit Maturity
NOT_DEFINED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
0.50%
Probability of exploitation in next 30 days
EPSS Percentile
39.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0050 is in the 18th percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
rustpatch availablevia ghsa
Product: cmovFixed in: 0.4.4

Vendor Advisories (1)

rustGHSA-2gqc-6j2q-83qphigh

RustCrypto Utilities cmov: `thumbv6m-none-eabi` compiler emits non-constant time assembly when using `cmovnz`

Jan 15, 2026

References

github.com / RustCrypto/utils/commit/55977257e7c82a309d5e8abfdd380a774f0f9778
Patch
github.com / RustCrypto/utils/security/advisories/GHSA-2gqc-6j2q-83qp
ExploitVendor Advisory