CVE-2021-21387Network attack vector

Message compromise via exposed keys and faulty verification

Published Mar 19, 2021 · Updated Aug 3, 2024

Cryptographic flaws in parabirb wrongthink before 2.2.0 allow remote attackers to compromise message confidentiality. The connection fingerprint exposes part of the secret identity key, the safety number incorporates only part of one public identity key instead of both keys, and DSA keys are only 1024 bits. Exploitation requires a user to connect or verify a peer, enabling interception or manipulation of supposedly end-to-end encrypted messages.

CVSS severity8.1
High
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cryptographic flaws in parabirb wrongthink before 2.2.0 allow remote attackers to compromise message confidentiality. The connection fingerprint exposes part of the secret identity key, the safety number incorporates only part of one public identity key instead of both keys, and DSA keys are only 1024 bits. Exploitation requires a user to connect or verify a peer, enabling interception or manipulation of supposedly end-to-end encrypted messages.

The record

CVE
CVE-2021-21387
Published
Mar 19, 2021
Updated
Aug 3, 2024
Vendor
Birb Digital
Product
Wrongthink
Classifications
CWE-319, CWE-326, CWE-358, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 19, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 2.0.0, < 2.2.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Birb Digital · Wrongthinkversion=>= 2.0.0, < 2.2.0

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:P/I:N/A:N
8.1GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/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-319Cleartext Transmission of Sensitive Information
CWE-326Inadequate Encryption Strength
CWE-358Improperly Implemented Security Check for Standard
T1557Adversary-in-the-Middle

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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