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Fencer Vulns
medium 5.3

CVE-2026-40012 json

Information about ECS zero scoped answers might leak to clients that use a specific ECS

published 2026-06-25 4 mo ago modified 2026-10-25 14 d ago also EUVD-2026-39356

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 39%
public exploits
0
none known

Summary

ECS zero scoped answers are stored in the packet cache while they should not. This impacts only configurations that have ECS enabled;

Patch / fix

  • PowerDNS Recursor 5.2.11, 5.3.8, 5.4.3
  • pdns-recursor Debian 13 5.2.11-0+deb13u1
  • pdns-recursor Debian 14 5.4.3-1

debian advisories DEBIAN-CVE-2026-40012

  • pdns-recursor Alpine 3.24 5.4.3-r0

alpine advisories ALPINE-CVE-2026-40012

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-2026-40012 updated cvss 5.3

pdns-recursor: information about ECS zero scoped answers might leak to clients that use a specific ECS

  • 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
partial
Assessed
4 mo ago

Exploit prediction

0.45% chance of exploitation in the next 30 days, higher than 39% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Affected products

  • PowerDNS Recursor

Classification

Weakness
  • CWE-524 Use of Cache Containing Sensitive Information

References

Sources

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.