CVE-2026-12244
Description
A flaw was found in nsd. When nsd is configured as a secondary server for a zone, a remote attacker, acting as the primary server for that zone, can send a specially crafted DNS message within an AXFR (Asynchronous Full Zone Transfer) request. This message, containing a malformed SVCB (Service Binding) resource record, can cause a heap overflow, leading to arbitrary code execution. This vulnerability poses a significant risk, especially in multi-tenant secondary DNS deployments, due to the potential for a controlled write of a large amount of data.
Statement
This Important vulnerability in NSD allows a remote attacker, acting as a configured primary DNS server, to trigger a heap overflow during an AXFR zone transfer. This can lead to arbitrary code execution on the secondary NSD server. The risk is particularly significant in multi-tenant environments where NSD serves as a secondary for multiple zones, as a compromised primary could exploit this flaw within NSD's trust boundary.
This vulnerability doesn't affect any supported Red Hat Product.
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
Write operations could cause memory corruption. In some cases, an adversary can modify control data such as return addresses in order to execute unexpected code.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
Attempting to access out-of-range, invalid, or unauthorized memory could cause the product to crash.
Other
Technical Impact: Unexpected State
Subsequent write operations can produce undefined or unexpected results.
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