CVE-2026-5947

SIG(0) validation during query flood may lead to undefined behavior

En bref

Sévérité: HIGH 7.5
EPSS: EPSS 1.39 % · centile 72 (2026-10-27)
État: PUBLISHED
Publiée: 2026-05-20
Mise à jour: 2026-09-01
Attribuée par: isc
Statut NVD: Modified

Description

Undefined behavior may result due to a race condition leading to a use-after-free violation. If BIND receives an incoming DNS message signed with SIG(0), it begins work to validate that signature. If, during that validation, the "recursive-clients" limit is reached (as would occur during a query flood), and that same DNS message is discarded per the limit, there is a brief window of time while the SIG(0) validation may attempt to read the now-discarded DNS message. This issue affects BIND 9 versions 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, and 9.20.9-S1 through 9.20.22-S1. BIND 9 versions 9.18.28 through 9.18.49 and 9.18.28-S1 through 9.18.49-S1 are NOT affected.

Scores

Version	Score	Vecteur	Évalué par
CVSS 3.1	HIGH 7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	isc
CVSS 3.1	HIGH 7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	redhat-SADP
CVSS 3.1	HIGH 7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	NVD · security-officer@isc.org (Secondary)
CVSS 3.1	MEDIUM 5.9	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H	NVD · nvd@nist.gov (Primary)
CVSS 3.1	HIGH 7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	NVD · 0b0ca135-0b70-47e7-9f44-1890c2a1c46c (Secondary)

Faiblesses (CWE)

Références européennes

ENISA EUVD · EUVD-2026-31110
GCVE · GCVE-0-2026-5947

Avis du CERT-FR

CERTFR-2026-AVI-0626 — Multiples vulnérabilités dans ISC BIND · cert.ssi.gouv.fr

Configurations affectées (CPE NVD)

cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:* ≥ 9.20.0 < 9.20.23
cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:* ≥ 9.21.0 < 9.21.22

Produits affectés

Produit	Versions
ISC · BIND 9	affected 9.20.0 ≤ 9.20.22 ; affected 9.21.0 ≤ 9.21.21 ; affected 9.20.9-S1 ≤ 9.20.22-S1 ; unaffected 9.18.28 ≤ 9.18.49 ; unaffected 9.18.28-S1 ≤ 9.18.49-S1

Références

Sources

Source	Licence
CVE List (CVEProject cvelistV5)	CVE Program Terms of Use
EPSS (FIRST.org)	FIRST — attribution requested
ENISA EUVD	ENISA — reproduction authorised, source acknowledged
CERT-FR (ANSSI)	Licence Ouverte / Etalab 2.0
NVD (NIST) via fkie-cad/nvd-json-data-feeds	Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD