Crypt::DSA versions before 1.21 for Perl reused the nonce across signatures, leading to private-key recovery

published 2026-06-15 4 mo ago modified 2026-10-25 14 d ago also EUVD-2026-37016

cvss: 9.1; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 21%
public exploits: 0; none known

Crypt::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.

Patch / fix

fixed in 1

TIMLEGGE Crypt::DSA 1.21

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-12205 updated 2026-06-28 cvss 7.1

Crypt::DSA: Crypt::DSA: Private-key recovery via nonce reuse across signatures

Red Hat All currently supported Red Hat products
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: yes
Technical impact: total
Assessed: 4 mo ago (2026-06-16)

Exploit prediction

0.29% chance of exploitation in the next 30 days, higher than 21% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	9.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CNA	3.1	9.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

TIMLEGGE Crypt::DSA

Classification

Weakness

CWE-323 Reusing a Nonce, Key Pair in Encryption

References

Sources

CVE List CVE-2026-12205
NVD CVE-2026-12205

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary