What is CVE-2025-27810?

CVE-2025-27810 is a medium-severity vulnerability in Arm Mbed TLS, classified under Use of Uninitialized Resource. CVSS score: 5.4/10. Published 2025-03-25.

How severe is CVE-2025-27810?

Medium severity. CVSS v3 base score is 5.4 out of 10.

Vulnerability in Arm Mbed TLS

CVE-2025-27810

Mbed TLS before 2.28.10 and 3.x before 3.6.3, in some cases of failed memory allocation or hardware errors, uses uninitialized stack memory to compose the TLS Finished message, potentially leading to authentication bypasses such as replays.

Published 2025-03-25 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (20.9th percentile), scored 2026-10-19.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 21st percentile — 20.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.000

Affected products

Weakness classification (CWE)

CWE-908 — Use of Uninitialized Resource

References

github.com/Mbed-TLS/mbedtls/releases (Release Notes)
mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory… (Vendor Advisory)

Frequently asked questions

What is CVE-2025-27810?: CVE-2025-27810 is a medium-severity vulnerability in Arm Mbed TLS, classified under Use of Uninitialized Resource. CVSS score: 5.4/10. Published 2025-03-25.
How severe is CVE-2025-27810?: Medium severity. CVSS v3 base score is 5.4 out of 10.