CVE-2021-36647

medium

Published 2023-01-17 · Modified 2026-06-05

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CVSS v3

4.7

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

CVSS v4 NEW

—

not yet in upstream

VIR risk

4.7

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.

Predictions

Exploit likelihood

47%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

OS impact

Debian Fixed 5 releases

Version	Status	Fixed in
trixie	Fixed	`2.16.11-0.1`
sid	Fixed	`2.16.11-0.1`
forky	Fixed	`2.16.11-0.1`
bullseye	Fixed	`2.16.9-0.1+deb11u1`
bookworm	Fixed	`2.16.11-0.1`

Application impact

Vendor	Product	Versions	Fixed
arm	mbed_tls	`{"endExcluding":"2.16.11"}`	`2.16.11`
arm	mbed_tls	`{"startIncluding":"2.17.0","endExcluding":"2.27.0"}`	`2.27.0`
trustedfirmware	mbed_tls	`{"startIncluding":"2.28.0","endExcluding":"3.0.0"}`	`3.0.0`

References

CWEs

CWE-327

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.