CVE-2026-12246
Description
A flaw was found in NSD. A remote attacker, operating as a configured primary DNS server in a multi-tenant secondary DNS deployment, could exploit a bug involving specially crafted Address Prefix List (APL) resource records. By providing an APL record with an adflength larger than permitted, the attacker can overwrite the stack when the zone is written to disk. This could lead to arbitrary code execution or a denial of service.
Statement
This is an Important flaw in NSD, affecting multi-tenant secondary DNS deployments. A remote attacker, acting as a configured primary DNS server, can exploit a specially crafted Address Prefix List (APL) resource record to cause a stack overwrite when the zone is written to disk. This could lead to arbitrary code execution or a denial of service on the secondary DNS server. The vulnerability requires the attacker to be a trusted primary, but the risk is significant in multi-tenant environments.
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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