CVE-2021-36647

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Summary

CVECVE-2021-36647
StatePUBLISHED
Assignermitre
Source PriorityCVE Program / NVD first with legacy fallback
Published2023-01-17 21:15:10 UTC
Updated2026-06-05 19:38:32 UTC
DescriptionUse 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.

Risk And Classification

Primary CVSS: v3.1 4.7 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

Problem Types: CWE-327 | n/a | CWE-327 CWE-327 Use of a Broken or Risky Cryptographic Algorithm

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary4.7MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
3.1ADPDECLARED4.7MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary4.7MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Arm Mbed Tls All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Na N/a affected n/a Not specified

References

ReferenceSourceLinkTags
kouzili.com/Load-Step.pdf af854a3a-2127-422b-91ae-364da2661108 kouzili.com Third Party Advisory
Releases · ARMmbed/mbedtls · GitHub af854a3a-2127-422b-91ae-364da2661108 github.com Third Party Advisory
Local side channel attack on RSA - Tech Updates - Mbed TLS (Previously PolarSSL) af854a3a-2127-422b-91ae-364da2661108 tls.mbed.org Vendor Advisory
lists.debian.org/debian-lts-announce/2025/06/msg00034.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Legacy QID Mappings

  • 183968 Debian Security Update for mbedtls (CVE-2021-36647)
  • 905280 Common Base Linux Mariner (CBL-Mariner) Security Update for fluent-bit (13023)
  • 906522 Common Base Linux Mariner (CBL-Mariner) Security Update for fluent-bit (13023-1)
  • 906626 Common Base Linux Mariner (CBL-Mariner) Security Update for fluent-bit (13023-3)

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