Internet Systems Consortium (ISC) on Wednesday rolled out a fresh round of BIND 9 updates to resolve four vulnerabilities, including two high-severity bugs.
Tracked as CVE-2026-3104, the first high-severity flaw is described as a memory leak issue impacting code preparing DNSSEC proofs of non-existence.
The security defect can be exploited via crafted domains to cause a memory leak in BIND resolvers. Authoritative servers may not be impacted, ISC notes in its advisory.
“If a BIND resolver is asked to query a specially crafted domain, memory will not be recovered by named. This can cause unbounded growth of Resident Set Size (RSS) memory, which may lead to an out-of-memory condition. Additionally, named will exit with an assertion failure if a shutdown or reload is attempted,” ISC explains.
The second high-severity vulnerability patched in the DNS software suite is CVE-2026-1519, which can lead to high CPU consumption when the resolver encounters a maliciously crafted zone during DNSSEC validation. This could lead to a sharp decrease in the number of handled queries.
While not recommended, disabling DNSSEC prevents the exploitation of this vulnerability, ISC notes.
Exploitation of both CVE-2026-3104 and CVE-2026-1519 can lead to denial of service (DoS), according to an advisory from Ubuntu, which provides BIND packages to its users.
The first medium-severity flaw addressed in the latest BIND releases is CVE-2026-3119, which could lead to unexpected named termination during the processing of a query containing a TKEY record.
The second is CVE-2026-3591, a use-after-return flaw in SIG(0) handling code that could lead to ACL bypass. The issue can be exploited via specially crafted DNS requests.
Patches for these security defects were included in BIND versions 9.18.47, 9.20.21, and 9.21.20, and in BIND Supported Preview Edition versions 9.18.47-S1 and 9.20.21-S1.
ISC says it is not aware of any of these vulnerabilities being exploited in the wild. Additional information can be found on its software updates page.
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