How severe is CVE-2026-23519?

CVE-2026-23519 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-23519 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (39th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-23519?

CVE-2026-23519 affects Rustcrypto Cmov. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-23519?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-23519 have an EU (EUVD) identifier?

Yes. CVE-2026-23519 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-2731.

When was CVE-2026-23519 published?

CVE-2026-23519 was published on 2026-01-15 and last updated on 2026-06-17.

CVE-2026-23519

CVE-2026-23519 is a critical-severity vulnerability in Rustcrypto Cmov with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-203.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v4: 8.9
EPSS exploit prediction: 0% (39th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-2731
Weakness: CWE-203
Affected product: Rustcrypto Cmov
Published: 2026-01-15
Last modified: 2026-06-17

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. 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.

Frequently asked questions

What is CVE-2026-23519?: 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.
How severe is CVE-2026-23519?: CVE-2026-23519 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-23519 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (39th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-23519?: CVE-2026-23519 affects Rustcrypto Cmov. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-23519?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-23519 have an EU (EUVD) identifier?: Yes. CVE-2026-23519 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-2731.
When was CVE-2026-23519 published?: CVE-2026-23519 was published on 2026-01-15 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:rustcrypto:cmov:*:*:*:*:*:rust:*:*

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