CVE-2023-4236 | named may terminate unexpectedly under high DNS-over-TLS query load

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.

Published: 2023-09-20 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-4236 is rated Moderate Risk (59.9/100): CVSS High severity, with medium exploitation likelihood (EPSS 2.15%). EPSS rose +1.97% over the last day, indicating growing attacker interest. Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-4236

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.18% 2.15% +1.97%
2 2025-12-28 0.13% 0.18% +0.05%
3 2025-12-27 — 0.13% —

Full EPSS history (17 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-4236

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2023-4236

OS Trackers for CVE-2023-4236

vendor priority summary link
alpine — CVE-2023-4236: 1 source package rows (bind); 36 state rows across 7 repos (3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 7, open 29. https://security.alpinelinux.org/vuln/CVE-2023-4236
debian unimportant CVE-2023-4236 unimportant priority: Debian including 1 source packages (bind9), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2023-4236
redhat high — https://access.redhat.com/security/cve/CVE-2023-4236
suse high CVE-2023-4236 severity important: SUSE including 49 source package names (bind, bind-9.18.19-1.1, …), 386 product×package rows across 40 product lines (SUSE CaaS Platform 4.0, SUSE Enterprise Storage 7.1, … (40 product lines)): Known Not Affected 369, Fixed 17. https://www.suse.com/security/cve/CVE-2023-4236/
ubuntu medium CVE-2023-4236 medium priority: Ubuntu including 2 source packages (bind9, isc-dhcp), 22 status rows across 11 suites (bionic, focal, jammy, lunar, mantic, noble, oracular, plucky, trusty, upstream, xenial): not-affected 14, released 7, needs-triage 1. https://ubuntu.com/security/CVE-2023-4236

Affected software / configurations for CVE-2023-4236

Vendor Product Version Raw CPE
isc bind >= 9.18.0, < 9.18.18 cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*
isc bind 9.18.11 cpe:2.3:a:isc:bind:9.18.11:s1:*:*:supported_preview:*:*:*
isc bind 9.18.18 cpe:2.3:a:isc:bind:9.18.18:s1:*:*:supported_preview:*:*:*
fedoraproject fedora 37 cpe:2.3:o:fedoraproject:fedora:37:*:*:*:*:*:*:*
fedoraproject fedora 38 cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:*
fedoraproject fedora 39 cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
debian debian_linux 11.0 cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
netapp h300s_firmware — cpe:2.3:o:netapp:h300s_firmware:-:*:*:*:*:*:*:*
netapp h500s_firmware — cpe:2.3:o:netapp:h500s_firmware:-:*:*:*:*:*:*:*
netapp h700s_firmware — cpe:2.3:o:netapp:h700s_firmware:-:*:*:*:*:*:*:*
netapp h410s_firmware — cpe:2.3:o:netapp:h410s_firmware:-:*:*:*:*:*:*:*
netapp h410c_firmware — cpe:2.3:o:netapp:h410c_firmware:-:*:*:*:*:*:*:*

References for CVE-2023-4236

cvelogic Threat Intelligence