CVE-2020-36421: arm mbed_tls Observable Discrepancy
CVSS: 5.3v3.1MediumModified
AliasesUBUNTU-CVE-2020-36421DEBIAN-CVE-2020-36421
Published 19-07-2021Last modified 03-12-2025
Vulnerability summary
CVE-2020-36421 is a medium (CVSS 5.3) Observable Discrepancy vulnerability in arm mbed_tls. EPSS estimates a 1.54% chance of exploitation in the next 30 days, higher than 74.5% of scored vulnerabilities. 1 public exploit is recorded.
CVSS score
5.3/10
010
Medium · v3.1 (CVE.org)EPSS score
1.54%
0%100%
Low · -0.04 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits1github
Advisory lineage
Upstream 0 · Downstream 1Timeline
- 19-07-2021PublishedVulnerability first disclosed.
- 03-12-2025Last modifiedVulnerability information updated.
Description
An issue was discovered in Arm Mbed TLS before 2.23.0. Because of a side channel in modular exponentiation, an RSA private key used in a secure enclave could be disclosed.
CVSS metrics
5 scores · 4 sources · 2 versionsMedium 5.3Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:NSourcesAll 4 agree
- OSV · UbuntuEcosystem advisory · calculated5.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- OSV · DebianEcosystem advisory · calculated5.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- NVDNIST5.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Medium 5.0Preferred score · NVD (NIST)
AV:N/AC:L/Au:N/C:P/I:N/A:NSourcesSingle source
EPSS trend
Probability
1.54%
Chance of exploitation in the next 30 days
Percentile
75%
Versus all other CVEs
30-day change
-0.04 pp
From 1.58% on 19-09-2026
19-09-202619-10-2026
EPSS score1.54%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
1 foundMbedtls
Maturity: poc
Weaknesses
CWE · root causeAffected systems
Debian2 products
- mbedtls< 2.16.9-0.1
- debian_linuxEOL10.0
Arm1 product
- mbed_tls< 2.16.7 | ≥ 2.17.0, < 2.23.0
Ubuntu1 product
- mbedtlsAll versions (No fix recorded)
3 vendors · 4 products
