Cmov
CVE-2026-23519
CRITICAL
GHSA-2gqc-6j2q-83qp
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessTarget ARM Cortex M0/M0+/M1 device
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ExploitDeploy RustCrypto CMOV <0.4.4
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ExecutionExploit timing side-channel in cmovnz
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ImpactExtract cryptographic secrets via power analysis
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V6 - Authentication Timing attack prevention
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| Exploitation Conditions | RustCrypto CMOV library version <0.4.4 compiled for thumbv6m-none-eabi (Cortex M0, M0+, M1 ARM processors). Attacker requires physical or side-channel access to measure timing/power consumption of the target device during cryptographic operations. |
| Impact | CVSS 9.8 (Critical). Network vector (timing observable over network). PoC available. Patch available. Affects embedded cryptographic implementations on popular IoT processors. EPSS 0.03%. |
| Exploit ScenarioDerived | An attacker measures the timing of cryptographic operations on an IoT device using a Cortex-M0, using statistical analysis to recover secret keys through the timing side channel. |
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Alert meAnalysisAIv1 – Mar 12, 2026
RustCrypto CMOV before 0.4.4 emits non-constant-time assembly on ARM Cortex-M0/M0+/M1 targets. Cryptographic operations that rely on constant-time guarantees are broken on these embedded platforms. PoC available, patch available.
Earlier versions of this analysis (1)
RustCrypto CMOV breaks constant-time guarantees on ARM Cortex-M0 targets, enabling timing side-channel attacks.
RemediationAI
Update to CMOV 0.4.4.
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in cargo
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
The cmovnz portable implementation compiles to branching (non-constant-time) assembly on thumbv6m-none-eabi (CWE-208). Cryptographic code using CMOV for secret-dependent operations leaks timing information.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Primary rating from GitHub Advisory · only source for this CVE.
CVSS VectorGitHub Advisory
Lifecycle Timeline
3DescriptionGitHub Advisory
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.
Executive ViewAI
Organizations using constant-time and not be rewritten as branches by the compiler. face critical risk from CVE-2026-23519 rated CVSS 9.8. Successful exploitation could critically impact the confidentiality, integrity, and availability of affected systems. Proof-of-concept code is publicly available, increasing the risk of exploitation. A patch is available and should be applied immediately given the critical severity.
Apply vendor patch. If immediate patching is not feasible: (1) Implement network-level access controls to limit exposure; (2) Enable enhanced monitoring and alerting; (3) Apply principle of least privilege.
Threat Intelligence Overview
NVD
CVE.org
EPSS
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
Exploit-DB