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Fencer Vulns
high 7.5

CVE-2023-4236 json

named may terminate unexpectedly under high DNS-over-TLS query load

published 2023-09-20 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-54109

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.2%
EPSS 2.2% chance of exploitation in 30 days, percentile 82%
public exploits
0
none known

Summary

A flaw in the networking code handling DNS-over-TLS queries may cause `named` to terminate unexpectedly due to an assertion failure. This happens when internal data structures are incorrectly reused under significant DNS-over-TLS query load. This issue affects BIND 9 versions 9.18.0 through 9.18.18 and 9.18.11-S1 through 9.18.18-S1.

Patch / fix

  • isc bind 9.18.18
  • bind9 Debian 12 1:9.18.19-1~deb12u1
  • bind9 Debian 14, Debian 13 1:9.19.17-1

debian advisories DEBIAN-CVE-2023-4236

  • bind9 Ubuntu 22.04 LTS 1:9.18.12-0ubuntu0.22.04.3
  • bind9 Ubuntu 24.04 LTS 1:9.18.18-0ubuntu2

ubuntu advisories UBUNTU-CVE-2023-4236

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • bind openSUSE Tumbleweed 9.18.19-1.1

opensuse advisories openSUSE-SU-2024:13249-1

  • bind Alpine 3.24, Alpine 3.23, Alpine 3.22 +5 more 9.18.19-r0

alpine advisories ALPINE-CVE-2023-4236

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-2023-4236 updated cvss 7.5

bind: an assertion failure may lead to DoS

  • Red Hat Enterprise Linux 6 bind, bind-sdb, bind-libs, bind-utils, bind-chroot Red Hat Enterprise Linux 7 bind, bind-sdb, bind-libs, bind-utils, bind-chroot, bind-pkcs11, +6 more Red Hat Enterprise Linux 8 bind, bind-sdb, bind9.16, bind-libs, bind-utils, bind-chroot, +14 more Red Hat Enterprise Linux 9 bind, bind-libs, bind-utils, bind-chroot, bind-license, python3-bind, +1 more
    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

Exploit prediction

2.19% chance of exploitation in the next 30 days, higher than 82% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • ISC BIND 9

Classification

Weakness

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.