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PatchSiren cyber security CVE debrief

CVE-2026-12205 TIMLEGGE CVE debrief

A vulnerability was discovered in Crypt::DSA versions before 1.21 for Perl, where the nonce was reused across signatures, allowing for private-key recovery. This is due to the caching of per-signature nonce material in the Key object without clearing it. As a result, keys used to sign more than once with an affected version should be considered compromised.

Vendor
TIMLEGGE
Product
Crypt::DSA
CVSS
CRITICAL 9.1
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-15
Original CVE updated
2026-06-16
Advisory published
2026-06-15
Advisory updated
2026-06-16

Who should care

Developers and users of Crypt::DSA versions before 1.21 for Perl should be aware of this vulnerability and take necessary actions to mitigate the risk.

Technical summary

The Crypt::DSA::sign function caches the per-signature nonce material in the Key object without clearing it. This causes the first sign() on a Key object to pick a nonce, and every later sign() on that same object to reuse it, producing an identical 'r' value.

Defensive priority

high

Recommended defensive actions

  • Upgrade to Crypt::DSA version 1.21 or later.
  • Consider replacing affected keys with new ones.

Evidence notes

The vulnerability was reported on the oss-security mailing list [ref-6]. The issue is documented in the Crypt::DSA source code [ref-4] and changelog [ref-5].

Sources and references

Verified primary and authoritative sources

  • CVE-2026-12205 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-12205

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-12205 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-12205

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source reference

    Unverified legacy reference

    URL: https://metacpan.org/release/TIMLEGGE/Crypt-DSA-1.20/source/lib/Crypt/DSA.pm

    9b29abf9-4ab0-4765-b253-1875cd9b441e

  • Source reference

    Unverified legacy reference

    URL: https://metacpan.org/release/TIMLEGGE/Crypt-DSA-1.21/changes

    9b29abf9-4ab0-4765-b253-1875cd9b441e

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.