CVE-2020-36476Network attack vector

Plaintext retention via incomplete buffer zeroization

Published Aug 23, 2021 · Updated Aug 4, 2024

Incomplete data removal in Mbed TLS before 2.24.0 allows attackers to cause unused application plaintext to remain in process memory. The mbedtls_ssl_read function fails to zero unused portions of its plaintext buffer after application data is read, leaving earlier bytes resident. The condition occurs when an application receives TLS plaintext through this API; public records do not identify a method for attackers to read the retained bytes.

CVSS severity7.5
High
EPSS probability1.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incomplete data removal in Mbed TLS before 2.24.0 allows attackers to cause unused application plaintext to remain in process memory. The mbedtls_ssl_read function fails to zero unused portions of its plaintext buffer after application data is read, leaving earlier bytes resident. The condition occurs when an application receives TLS plaintext through this API; public records do not identify a method for attackers to read the retained bytes.

The record

CVE
CVE-2020-36476
Published
Aug 23, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-212
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 23, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-212Improper Removal of Sensitive Information Before Storage or Transfer

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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