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FedoraOperating system · Fedoraproject

CVE-2021-45450

HIGH · 7.5 CVSS v3.1 Published 2021-12-21
Fix available
A fix is available. Upgrade to 2.28.0 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In Mbed TLS before 2.28.0 and 3.x before 3.1.0, psa_cipher_generate_iv and psa_cipher_encrypt allow policy bypass or oracle-based decryption when the output buffer is at memory locations accessible to an untrusted application.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

In Mbed TLS before 2.28.0 and 3.x before 3.1.0, the psa_cipher_generate_iv and psa_cipher_encrypt functions allow policy bypass or oracle-based decryption when the output buffer resides at memory locations accessible to an untrusted application. An attacker who controls or can observe the output buffer location can potentially decrypt data or bypass cryptographic policy checks.

MitigationUpgrade Mbed TLS to version 2.28.0 or 3.1.0 or later. Review any code using psa_cipher_generate_iv and psa_cipher_encrypt to ensure output buffers are not placed in memory regions accessible to untrusted code.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FedoraOperating system
Affected:= 36= 37
Mbed TlsApplication
Affected:>= 2.22.0, < 2.28.0= 3.0.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Mbed TLS version
    Check the Mbed TLS library version by examining the installed package or library file. On Linux systems, use 'rpm -q mbedtls' or check for libmbedtls version files. If Mbed TLS is embedded in an application, check the application's dependencies or documentation for the bundled Mbed TLS version.
    Affected if The version is 2.22.0 through 2.27.x, or exactly 3.0.0, indicating a vulnerable version.
  2. Locate Mbed TLS header files
    Find the mbedtls version header file (commonly mbedtls/version.h or include/mbedtls/version.h) and read the MBEDTLS_VERSION_NUMBER or MBEDTLS_VERSION_MAJOR/MINOR/PATCH macros to determine the exact version.
    Affected if The version retrieved is < 2.28.0 for the 2.x branch, or = 3.0.0 for the 3.x branch.
  3. Identify usage of vulnerable functions
    Search source code for calls to psa_cipher_generate_iv or psa_cipher_encrypt functions. Use grep or similar tools: 'grep -r "psa_cipher_generate_iv\|psa_cipher_encrypt" --include="*.c" --include="*.h"' in the project source.
    Affected if These functions are present in the codebase and are called with output buffers that may be accessible to untrusted code.
  4. Assess output buffer memory accessibility
    Review the memory allocation patterns for the output buffers passed to psa_cipher_generate_iv and psa_cipher_encrypt. Determine if these buffers are allocated on the heap, stack, or in memory regions that could be observed or controlled by untrusted application code.
    Affected if Output buffers are placed in memory accessible to untrusted code, such as shared memory, memory-mapped files, or memory allocated by untrusted components.

You are affected if your Mbed TLS version is between 2.22.0 and 2.27.x inclusive, or exactly 3.0.0, AND your code uses psa_cipher_generate_iv or psa_cipher_encrypt with output buffers in attacker-observable or accessible memory.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2.28.0 or later
Fixed in 2.28.0
Interim mitigation

Upgrade Mbed TLS to version 2.28.0 or 3.1.0 or later. Review any code using psa_cipher_generate_iv and psa_cipher_encrypt to ensure output buffers are not placed in memory regions accessible to untrusted code.

Recommended fix High confidence

Mbed TLS 2.x -> 2.28.0 or later; Mbed TLS 3.x -> 3.1.0 or later

  1. Identify the Mbed TLS version in use by checking project dependencies or library version
  2. For Mbed TLS 2.x (versions 2.22.0 through 2.27.x): upgrade to version 2.28.0 or later
  3. For Mbed TLS 3.x (version 3.0.0): upgrade to version 3.1.0 or later
  4. For Fedora systems: run 'dnf update mbedtls' after the fixed packages are available in the Fedora repositories
  5. Rebuild and redeploy any applications statically linked against the vulnerable Mbed TLS library
  6. Verify the fix by confirming psa_cipher_generate_iv and psa_cipher_encrypt no longer allow IV manipulation when output buffer is in untrusted memory
Caveat Minor: Check release notes for any API changes between 2.x/3.x branches; when upgrading from 2.x to 3.x review migration guide for breaking changes

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Fedora Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing16.0 h
  • Review / QA4.0 h
32.0 hours of engineering $5,360
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-45450 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data