CVE-2023-4236named may terminate unexpectedly under high DNS-over-TLS query load
- 7.5HighCVSS base score
- 2.2%Exploitation in 30 daysEPSS · top 17% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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.
Timeline
ID reserved
By isc
- 43 days later
· 43 days later
Published
- 17 months later
· 17 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| iscCNA (assigner) | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| NVDNVD · Modified | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 2.2% · top 17% of all CVEs (12 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Affected products
What to do
Solution: Upgrade to the patched release most closely related to your current version of BIND 9: 9.18.19 or 9.18.19-S1.
Workaround: Disabling listening for DNS-over-TLS connections (by removing `listen-on ... tls ... { ... };` statements from the configuration) prevents the affected code paths from being taken, rendering exploitation impossible. However, there is no workaround for this flaw if DNS-over-TLS support is required.
Exploitation: We are not aware of any active exploits.
References
References7
- CVE-2023-4236 (opens in a new tab)vendor-advisoryx_transferred
- http://www.openwall.com/lists/oss-security/2023/09/20/2 (opens in a new tab)x_transferred
- https://www.debian.org/security/2023/dsa-5504 (opens in a new tab)x_transferred
- https://lists.fedoraproject.org/archives/list/[email protected]/message/IPJLLTJCSDJJII7IIZPLTBQNWP7MZH7F/ (opens in a new tab)x_transferred
- https://lists.fedoraproject.org/archives/list/[email protected]/message/U35OARLQCPMVCBBPHWBXY5M6XJLD2TZ5/ (opens in a new tab)x_transferred
- https://security.netapp.com/advisory/ntap-20231013-0004/ (opens in a new tab)x_transferred
- https://lists.fedoraproject.org/archives/list/[email protected]/message/VSK5V4W4OHPM3JTJGWAQD6CZW7SFD75B/ (opens in a new tab)x_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2023-54109 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2023-4236)Record last updated .