4.7

CVE-2021-36647: arm mbed_tls

CVSS: 4.7v3.1MediumModified
AliasesUBUNTU-CVE-2021-36647DEBIAN-CVE-2021-36647
Published 17-01-2023Last modified 03-11-2025
Open JSON

Vulnerability summary

CVE-2021-36647 is a medium (CVSS 4.7) vulnerability in arm mbed_tls. EPSS estimates a 0.16% chance of exploitation in the next 30 days, higher than 5.3% of scored vulnerabilities.

Overall risk
19/100
0100
Low · default modelHow is this calculated?
CVSS score
4.7/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.16%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 1
DLA-4236-1

Timeline

  1. 17-01-2023
    PublishedVulnerability first disclosed.
  2. 03-11-2025
    Last modifiedVulnerability information updated.

Description

Use of a Broken or Risky Cryptographic Algorithm in the function mbedtls_mpi_exp_mod() in lignum.c in Mbed TLS Mbed TLS all versions before 3.0.0, 2.27.0 or 2.16.11 allows attackers with access to precise enough timing and memory access information (typically an untrusted operating system attacking a secure enclave such as SGX or the TrustZone secure world) to recover the private keys used in RSA.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.16%

Chance of exploitation in the next 30 days

Percentile

5%

Versus all other CVEs

30-day change

0.00 pp

From 0.16% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.16%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Arm1 product
  • mbed_tls< 2.16.11 | ≥ 2.17.0, < 2.27.0
Debian1 product
  • mbedtls< 2.16.11-0.1
Trustedfirmware1 product
Ubuntu1 product
  • mbedtlsAll versions (No fix recorded)

4 vendors · 4 products

References

8 links