Wildcard CNAME proof validation bypass

published 2026-07-23 3 mo ago modified 2026-10-24 15 d ago also EUVD-2026-47931

cvss: 3.7; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 5%
public exploits: 0; none known

The issue is a DNSSEC validation bypass where wildcard expansion proofs (NSEC/NSEC3 records) are accepted without signature validation when the wildcard answer is a CNAME or DNAME record.

Patch / fix

fixed in 1 distros 2

PowerDNS Recursor 5.2.12, 5.3.9, 5.4.4

debian alpine

pdns-recursor Debian 13 5.2.12-0+deb13u1
pdns-recursor Debian 14 5.4.4-1

debian advisories DEBIAN-CVE-2026-52686

pdns-recursor Alpine 3.24 5.4.4-r0

alpine advisories ALPINE-CVE-2026-52686

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

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-2026-52686 updated 2026-07-27 cvss 3.7

pdns-recursor: pdns-recursor: DNSSEC validation bypass due to unsigned wildcard expansion proofs

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: no
Technical impact: partial
Assessed: 3 mo ago (2026-07-23)

Exploit prediction

0.16% chance of exploitation in the next 30 days, higher than 5% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	3.7	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected products

PowerDNS Recursor

Classification

Weakness

CWE-347 Improper Verification of Cryptographic Signature

References

docs.powerdns.com /recursor/security-advisories/powerdns-advisory-powerdns-2026-10.html

Sources

CVE List CVE-2026-52686
NVD CVE-2026-52686

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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary