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WrongthinkApplication

CVE-2021-21387

HIGH · 7.5 CVSS v3.1 Published 2021-03-19
Fix available
A fix is available. Upgrade to 2.3.0 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
Wrongthink peer-to-peer, end-to-end encrypted messenger with PeerJS and Axolotl ratchet. In wrongthink from version 2.0.0 and before 2.3.0 there was a set of vulnerabilities causing inadequate encryption strength. Part of the secret identity key was disclosed by the fingerprint used for connection. Additionally, the safety number was improperly calculated. It was computed using part of one of the public identity keys instead of being derived from both public identity keys. This caused issues in computing safety numbers which would potentially be exploitable in the real world. Additionally there was inadequate encryption strength due to use of 1024-bit DSA keys. These issues are all fixed in version 2.3.0.

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 · high confidence

The wrongthink messenger had multiple cryptographic flaws: (1) the fingerprint used for peer connections disclosed part of the user's secret identity key, (2) safety numbers were incorrectly computed using only a portion of one public identity key rather than deriving from both parties' keys, and (3) the system used cryptographically weak 1024-bit DSA keys which are vulnerable to factorization attacks.

MitigationUpgrade to wrongthink version 2.3.0 or later, which replaces 1024-bit DSA keys with stronger cryptography, fixes the safety number derivation to use both identity keys, and removes the secret key disclosure in fingerprints.

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
WrongthinkApplication
Affected:>= 2.0.0, < 2.3.0

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. Verify Wrongthink is installed
    Check for the presence of Wrongthink application or its executable/package on the system. Look for wrongthink binary, wrongthink package, or the application installed via package manager.
    Affected if Wrongthink is found installed on the system
  2. Determine installed Wrongthink version
    Run 'wrongthink --version' or check the installed package version via package manager (e.g., 'dpkg -l wrongthink' or 'rpm -qi wrongthink'). Compare the version number to the affected range.
    Affected if Version is >= 2.0.0 and < 2.3.0
  3. Inspect key generation parameters
    Examine Wrongthink's configuration or key storage directory for DSA key parameters. Look in ~/.config/wrongthink/keys/ or similar directory for key files. Check if any stored keys show 'DSA' or '1024' bit length in their metadata.
    Affected if 1024-bit DSA keys are present in the key storage
  4. Verify fingerprint configuration
    Check the peer connection fingerprint settings or export a contact's fingerprint using wrongthink CLI (e.g., 'wrongthink fingerprint' or inspect the saved fingerprint in contact database). Determine if fingerprints expose portions of identity keys.
    Affected if Fingerprints expose parts of the secret identity key to peers
  5. Check safety number derivation
    Generate a safety number for an existing contact using wrongthink CLI (e.g., 'wrongthink safetynumber <contact>'). Compare the computed value against what would be derived from full identity key pairs rather than partial key data.
    Affected if Safety numbers are computed using only a portion of one public identity key

A user is affected if Wrongthink version is >= 2.0.0 and < 2.3.0 and the application is actively used for peer connections with the vulnerable cryptographic implementations.

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.

From vendor data
Upgrade available Upgrade to 2.3.0 or later
Fixed in 2.3.0
Interim mitigation

Upgrade to wrongthink version 2.3.0 or later, which replaces 1024-bit DSA keys with stronger cryptography, fixes the safety number derivation to use both identity keys, and removes the secret key disclosure in fingerprints.

Fix this in Wrongthink Scoped from the published advisory
  • Consultation2.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,800
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,480.

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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-2021-21387 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