CVE-2025-66442

In Mbed TLS through 4.0.0, there is a compiler-induced timing side channel (in RSA and CBC/ECB decryption) that only occurs with LLVM's select-optimize feature. TF-PSA-Crypto through 1.0.0 is also affected.

Published: 2026-04-01 Last update: 2026-04-03 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-66442 is rated Low Risk (21.2/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.01%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-66442

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-02 — 0.01% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-66442

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.1 3.1 MEDIUM
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 1.4 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2025-66442

OS Trackers for CVE-2025-66442

vendor priority summary link
debian unimportant CVE-2025-66442 unimportant priority: Debian including 1 source packages (mbedtls), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 5. https://security-tracker.debian.org/tracker/CVE-2025-66442
redhat medium — https://access.redhat.com/security/cve/CVE-2025-66442
ubuntu medium CVE-2025-66442 medium priority: Ubuntu including 1 source packages (mbedtls), 7 status rows across 7 suites (bionic, focal, jammy, noble, questing, upstream, xenial): deferred 7. https://ubuntu.com/security/CVE-2025-66442

Affected software / configurations for CVE-2025-66442

Vendor Product Version Raw CPE
arm mbed_tls <= 4.0.0 cpe:2.3:a:arm:mbed_tls:*:*:*:*:*:*:*:*
arm tf-psa-crypto <= 1.0.0 cpe:2.3:a:arm:tf-psa-crypto:*:*:*:*:*:*:*:*

References for CVE-2025-66442

cvelogic Threat Intelligence