CVE-2026-12244
Heap overflow and crash with crafted SVCB RR
Description
If NSD is configured as secondary for a zone, the primary of that zone can crash NSD with an AXFR containing a DNS message with a special crafted SVCB RR with an rdata size of 65512, that let's an (uint16_t) variable that is used to allocate space needed for the RR wrap (because total size > 65535), causing a heap overflow. The attacker can perform a controlled (RCE class) head write of up to 65509 bytes
INFO
Published Date :
June 25, 2026, 5:24 a.m.
Last Modified :
June 25, 2026, 5:24 a.m.
Remotely Exploit :
Yes !
Source :
NLnet Labs
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | HIGH | 206fc3a0-e175-490b-9eaa-a5738056c9f6 | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update NSD to the latest version.
- Apply security patches provided by the vendor.
- Reconfigure zones to use secure AXFR transfer settings.
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