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Fencer Intel
medium 6.2

CVE-2025-54764 json

Side channel in RSA key generation and operations (SSBleed, M-Step)

published last yr. modified 4d ago also EUVD-2025-35113 , JLSEC-2025-232

cvss
6.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 12%
public exploits
0
none known

Summary

Mbed TLS before 3.6.5 allows a local timing attack against certain RSA operations, and direct calls to mbedtls_mpi_mod_inv or mbedtls_mpi_gcd.

Patch / fix

  • arm mbed_tls 3.6.5
  • mbedtls Debian 13 3.6.5-0.1~deb13u1
  • mbedtls Debian 14 3.6.5-0.1

debian advisories DEBIAN-CVE-2025-54764

  • mbedtls openSUSE Leap 16.0 3.6.6-bp160.1.1
  • mbedtls openSUSE Tumbleweed 3.6.5-1.1

opensuse advisories openSUSE-SU-2026:21144-1openSUSE-SU-2025:15747-1

  • mbedtls Alpine 3.24, Alpine 3.23, Alpine 3.22 +2 more 3.6.5-r0
  • mbedtls3 Alpine 3.24 3.6.5-r0

alpine advisories ALPINE-CVE-2025-54764

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2025-54764 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-54764 updated cvss 4.7

mbedtls: Mbedtls timing attacks in RSA operations

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last yr.

Exploit prediction

0.22% chance of exploitation in the next 30 days, higher than 12% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • mbed-tls.readthedocs.io https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2025-10-ssbleed-mstep/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 6.2 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CNA 3.1 6.2 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
OSV 3.1 6.2 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
julia MbedTLS_jll
all versions
 no fix listed

Classification

Weakness
  • CWE-208 Observable Timing Discrepancy

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.