CVE-2026-23519: RustCrypto utils · Timing Side Channel
Affects RustCrypto utilsSource CVE Database V5
Not known to be exploited · CVSS 8.9 High : upgrade to 0.4.4 soon.
Data as of 26 Oct 2026, 06:26 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 46% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 0.4.4
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 15 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.
What to do
Upgrade utils and github/RustCrypto/utils to 0.4.4.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| RustCryptoutils | Affected
| Fixed in
|
crates.iogithub/RustCrypto/utilspkg:cargo/github/RustCrypto/utilsOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
European organizations should immediately audit their embedded device inventories to identify those running RustCrypto utils versions earlier than 0.4.4 on Cortex M0, M0+, or M1 processors. They should prioritize upgrading RustCrypto utils to version 0.4.4 or later, which contains the fix ensuring constant-time execution of cmovnz instructions. For devices where updates are not feasible, organizations should consider compensating controls such as isolating vulnerable devices on segmented networks, implementing strict access controls, and monitoring for anomalous timing-based side-channel attack attempts. Developers should review cryptographic implementations for constant-time guarantees, especially when targeting embedded platforms with constrained compilers. Additionally, organizations should engage with device vendors to confirm patch availability and deployment plans. Incorporating side-channel resistance testing into the development and procurement lifecycle can help prevent similar vulnerabilities. Finally, maintaining robust incident response plans for embedded device compromise scenarios is recommended.
Description
CVE-2026-23519 is a high-severity vulnerability in RustCrypto utils prior to version 0.4.4, where the conditional move CPU intrinsic (cmovnz) does not execute in constant time on the thumbv6m-none-eabi platform (Cortex M0, M0+, M1). This timing discrepancy can lead to observable side-channel leaks, potentially exposing sensitive information. The flaw arises because the compiler emits non-constant time assembly code, violating the constant-time guarantee critical for cryptographic operations. No known exploits are currently in the wild, but the vulnerability affects embedded systems using these RustCrypto utils on vulnerable platforms. The issue is fixed in version 0.4.4. European organizations using embedded devices with Cortex M0/M0+/M1 processors and RustCrypto utils versions before 0.