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NVD / CVE Program· CNA mitre

CVE-2021-24119: In Trusted Firmware Mbed TLS 2.24.0, a side-channel vulnerability in base64 PEM file decoding allows system-level (administrator) attackers…

MediumCVSS 4.9 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 19/100)

  • 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: 1.4% (FIRST EPSS); higher than 74.3% of all records.
  • Anyone who can reach it over the internet can trigger it. Administrator privileges are required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: mbedtls (Debian:10) 2.16.9-0~deb10u1; mbedtls (Debian:11) 2.16.9-0.1+deb11u1; mbedtls (Debian:12) 2.16.11-0.1.

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) 2.16.11-0.1 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

In Trusted Firmware Mbed TLS 2.24.0, a side-channel vulnerability in base64 PEM file decoding allows system-level (administrator) attackers to obtain information about secret RSA keys via a controlled-channel and side-channel attack on software running in isolated environments that can be single stepped, especially Intel SGX.

Published
Jul 14, 2021
Updated
Jun 16, 2026
EPSS
1.4% · 74th percentile

Report tools

JSON

Action score

19

Monitor

Low priority for now.

CVSS
19 / 40 · 4.9 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.4%

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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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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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.

VendorProduct
armmbed tls
fedoraprojectfedora
debiandebian linux

Check your server's TLS configuration

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 tlsbefore 2.26.0
  • debian debian linux10.0
  • debian debian linux9.0
  • fedoraproject fedora33
  • fedoraproject fedora34

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:10mbedtlsbefore 2.16.9-0~deb10u12.16.9-0~deb10u1
Debian:11mbedtlsbefore 2.16.9-0.1+deb11u12.16.9-0.1+deb11u1
Debian:12mbedtlsbefore 2.16.11-0.12.16.11-0.1
Debian:9mbedtlsbefore 2.4.2-1+deb9u42.4.2-1+deb9u4
openSUSE:Leap 15.2mbedtlsbefore 2.16.9-lp152.2.6.12.16.9-lp152.2.6.1
openSUSE:Leap 15.3mbedtlsbefore 2.16.9-bp153.2.5.12.16.9-bp153.2.5.1
openSUSE:Tumbleweedmbedtls-2before 2.27.0-2.12.27.0-2.1
openSUSE:Tumbleweedmbedtls-3before 3.6.6-1.13.6.6-1.1
SUSE:Package Hub 15 SP2mbedtlsbefore 2.16.9-bp152.2.6.12.16.9-bp152.2.6.1
SUSE:Package Hub 15 SP3mbedtlsbefore 2.16.9-bp153.2.5.12.16.9-bp153.2.5.1

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-2020-10932Apr 15, 2020 · An issue was discovered in Arm Mbed TLS before 2.16.6 and 2.7.x before 2.7.15.
    18Monitor
  • ← EarlierCVE-2020-16150Sep 2, 2020 · A Lucky 13 timing side channel in mbedtls_ssl_decrypt_buf in library/ssl_msg.c in Trusted Firmware Mbed TLS through 2.23.0 allows an…
    22Monitor
  • Later →CVE-2020-36421Jul 19, 2021 · An issue was discovered in Arm Mbed TLS before 2.23.0.
    21Monitor

Remediation

Which version to upgrade to

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

Product / packageFixed versionSource
debian:mbedtls2.16.11-0.1 · Debian:12Package registry (OSV)
opensuse:mbedtls2.16.9-bp153.2.5.1 · openSUSE:Leap 15.3Package registry (OSV)
opensuse:mbedtls2.16.9-lp152.2.6.1 · openSUSE:Leap 15.2Package registry (OSV)
opensuse:mbedtls-22.27.0-2.1 · openSUSE:TumbleweedPackage registry (OSV)
opensuse:mbedtls-33.6.6-1.1 · openSUSE:TumbleweedPackage registry (OSV)
suse:mbedtls2.16.9-bp152.2.6.1 · SUSE:Package Hub 15 SP2Package registry (OSV)
suse:mbedtls2.16.9-bp153.2.5.1 · SUSE:Package Hub 15 SP3Package 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.

Bug bounty scope

The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • Administrator privileges are required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
none
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
High
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
None
Availability impact
None

Weakness class (CWE)

CWE-203 · Observable Discrepancy

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

References

Show all references (6 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records