Vulnerability · Published Jun 25, 2026 · Assigned by NLnet Labs
CVE-2026-12245Denial of DNS over TLS service by any DoT client
High 8.7
In plain English
A high-severity use-after-free in NSD from NLnet Labs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 40% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 4.0)8.7High
Exploit odds (30 days)0.5%top 59.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
NSD from version 4.13.0 has a heap use-after-free bug in logging errors on TLS connections, causing a crash of the server process, which can be triggered trivially by sending a DNS query over a DoT connection, and closing the connection without reading the response.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.24 | nsd | 4.14.3-r0 | ALPINE-CVE-2026-12245 |
| Debian:14 | nsd | 4.14.3-1 | DEBIAN-CVE-2026-12245 |
| Ubuntu:25.10 | nsd | no fix listed | UBUNTU-CVE-2026-12245 |
| Ubuntu:26.10 | nsd | no fix listed | UBUNTU-CVE-2026-12245 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| NLnet Labs | NSD | 4.13.0 – before 4.14.3 |
Weakness: CWE-416 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
References
- https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-12245.txt vendor-advisory