CVE-2021-45450Network attack vector

Decryption oracle via shared-buffer readback

Published Dec 21, 2021 · Updated Aug 4, 2024

Cryptographic policy bypass in Mbed TLS before 2.28.0 and 3.x before 3.1.0 allows attackers to decrypt protected data through an oracle. The psa_cipher_generate_iv and psa_cipher_encrypt functions read back data from output buffers instead of treating those buffers as write-only. Exploitation requires an output buffer in memory shared with an untrusted application, enabling policy bypass or oracle-based plaintext recovery.

CVSS severity7.5
High
EPSS probability1.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cryptographic policy bypass in Mbed TLS before 2.28.0 and 3.x before 3.1.0 allows attackers to decrypt protected data through an oracle. The psa_cipher_generate_iv and psa_cipher_encrypt functions read back data from output buffers instead of treating those buffers as write-only. Exploitation requires an output buffer in memory shared with an untrusted application, enabling policy bypass or oracle-based plaintext recovery.

The record

CVE
CVE-2021-45450
Published
Dec 21, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-327
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 21, 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

7.5NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
5.0NISTAV:N/AC:L/Au:N/C:P/I:N/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-327Use of a Broken or Risky Cryptographic Algorithm

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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