NVD / CVE Program· CNA mitre

CVE-2021-43666: A Denial of Service vulnerability exists in mbed TLS 3.0.0 and earlier in the mbedtls_pkcs12_derivation function when an input password's…

Noroxi assessment

Priority: Monitor (action score 31/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 2% (FIRST EPSS); higher than 81.5% of all records.
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
According to CISA the attack is automatable: targets can be found by mass scanning.
Fixed version: mbedtls (Debian:10) 2.16.9-0~deb10u1; mbedtls (Debian:11) 2.16.9-0.1+deb11u1; mbedtls (Debian:12) 2.28.0-1.

Low priority for now. Upgrade to mbedtls (Debian:10) 2.16.9-0~deb10u1; mbedtls (Debian:11) 2.16.9-0.1+deb11u1; mbedtls (Debian:12) 2.28.0-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

A Denial of Service vulnerability exists in mbed TLS 3.0.0 and earlier in the mbedtls_pkcs12_derivation function when an input password's length is 0.

HighCVSS 7.5 · v3.1—No exploit Fix available

Published: Mar 24, 2022
Updated: Jun 17, 2026
EPSS: 2.0% · 81th percentile
CWE: CWE-130

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 30 / 40 · 7.5 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 1 / 30 · 2.0%

CISA SSVC decision

Exploitation: proof of concept
Automatable: yes
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
arm	mbed tls	cpe:2.3:a:arm:mbed_tls
debian	debian linux	cpe:2.3:o:debian:debian_linux

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The Mbed TLS version can't be seen from outside; the free SSL checker tests your certificate, enabled TLS versions and weak ciphers. Confirm the version on your server with the package manager.

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Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

arm mbed tlsup to 3.0.0 inclusive
debian debian linux10.0

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:10	mbedtls	before 2.16.9-0~deb10u1	2.16.9-0~deb10u1
Debian:11	mbedtls	before 2.16.9-0.1+deb11u1	2.16.9-0.1+deb11u1
Debian:12	mbedtls	before 2.28.0-1	2.28.0-1

Same product

arm: all records

Other highest-scoring records for the same primary product.

CVE-2025-47917Mbed TLS before 3.6.4 allows a use-after-free in certain situations of applications that are developed in accordance with the documentation.
40Plan
CVE-2021-44732Mbed TLS before 3.0.1 has a double free in certain out-of-memory conditions, as demonstrated by an mbedtls_ssl_set_session() failure.
40Plan
CVE-2017-18187In ARM mbed TLS before 2.7.0, there is a bounds-check bypass through an integer overflow in PSK identity parsing in the…
40Plan

Published before and after this one in the same product

← EarlierCVE-2020-36478Aug 22, 2021 · An issue was discovered in Mbed TLS before 2.25.0 (and before 2.16.9 LTS and before 2.7.18 LTS).
30Monitor
← EarlierCVE-2021-45451Dec 21, 2021 · In Mbed TLS before 3.1.0, psa_aead_generate_nonce allows policy bypass or oracle-based decryption when the output buffer is at memory…
30Monitor
Later →CVE-2022-35409Jul 15, 2022 · An issue was discovered in Mbed TLS before 2.28.1 and 3.x before 3.2.0.
37Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
debian:mbedtls	2.28.0-1 · Debian:12	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

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Bug bounty scope