CVE-2026-12205
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 · uneditedCrypt::DSA versions before 1.21 for Perl reused the nonce across signatures, leading to private-key recovery. Crypt::DSA::sign caches the per-signature nonce material in the Key object without ever clearing it. The first sign() on a Key object picks a nonce, and every later sign() on that same object reuses it, producing an identical "r". Keys used to sign more than once with an affected version should be considered compromised.
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 confidenceCrypt::DSA versions before 1.21 cache the per-signature nonce in the Key object without clearing it after use. The first sign() call picks a nonce and all subsequent signatures on that Key object reuse it, producing identical 'r' values. This nonce reuse allows attackers to mathematically recover the DSA private key from multiple signatures.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 checksWork through these to decide whether this CVE applies to you.
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Check Crypt::DSA versionRun 'perl -MCrypt::DSA -e "print $Crypt::DSA::VERSION"' or check via CPAN/cpanm listingAffected if Version is below 1.21 (e.g., 1.20, 1.19, etc.)
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Inspect key usage patternsReview application code or logs for any Key object used in multiple sign() calls without being re-createdAffected if The same DSA Key object was used to generate more than one signature
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Examine signature outputs for nonce reuseIf you have access to existing signatures made with the vulnerable library, compare the 'r' value in multiple signatures from the same keyAffected if Multiple signatures from the same key show identical 'r' values (indicating nonce was reused)
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Verify key generation methodCheck whether keys were generated using Crypt::DSA::Key or similar constructors from the affected libraryAffected if DSA keys were created with Crypt::DSA versions before 1.21
You are affected if Crypt::DSA version is below 1.21 AND any DSA key was used to create more than one signature, as this triggers the nonce reuse vulnerability.
Generated from the published advisory. Verify against your own configuration.
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 · scopedUpgrade Crypt::DSA to version 1.21 or later, and treat all DSA keys that were used to sign more than once with affected versions as compromised—regenerate these keys and re-sign any data.
1.21
- Upgrade Crypt::DSA to version 1.21 or later using your Perl package manager (cpan or cpanm): 'cpanm Crypt::DSA' or 'cpan Crypt::DSA'
- After upgrading, regenerate any DSA private keys that were used to sign more than one message with the affected (pre-1.21) version, as these keys should be considered compromised
- Verify the installed version with 'perl -MCrypt::DSA -e 'print $Crypt::DSA::VERSION'' to confirm the upgrade was successful
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,304.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-12205 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-12205 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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