SB2026091801 - Debian update for bind9
Published: September 18, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 12 vulnerabilities.
1) Insufficient verification of data authenticity (CVE-ID: CVE-2026-19033)
CWE-ID: CWE-345 - Insufficient Verification of Data Authenticity
CVSSv4: 8.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to add arbitrary data to a zone.
The vulnerability exists due to improper verification of TSIG signatures in named IXFR processing when processing a multi-message TCP IXFR for a TSIG-restricted secondary zone. A remote attacker can send an IXFR transfer without a valid TSIG signature to add arbitrary data to a zone.
2) Use-after-free (CVE-ID: CVE-2026-19662)
CWE-ID: CWE-416 - Use After Free
CVSSv4: 8.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to a use-after-free in qpcache NOQNAME proof handling when processing crafted DNSSEC responses from an attacker-controlled authoritative server. A remote attacker can send a particular sequence of crafted DNS answers to cause a denial of service.
Exploitation requires inducing the resolver to issue multiple queries for a DNSSEC-signed zone and relies on the responses arriving in a particular order and with particular timing.
3) Use-after-free (CVE-ID: CVE-2026-19666)
CWE-ID: CWE-416 - Use After Free
CVSSv4: 8.7 [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]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to use-after-free in query_addnoqnameproof() via the DNS64 filter64 path when processing a malformed applicable answer from an authoritative server. A remote attacker can send a malformed applicable DNS answer to cause a denial of service.
Only resolvers configured to use dns64 are affected.
4) Numeric Truncation Error (CVE-ID: CVE-2026-19667)
CWE-ID: CWE-197 - Numeric Truncation Error
CVSSv4: 8.7 [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]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to numeric truncation in dns_ncache_add() when processing a negative answer exactly 65536 bytes long from an attacker-controlled authoritative server. A remote attacker can return such a negative answer to cause a denial of service.
5) Resource exhaustion (CVE-ID: CVE-2026-19668)
CWE-ID: CWE-400 - Resource exhaustion
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to uncontrolled resource consumption in the BIND recursive resolver when processing large numbers of invalid DNSSEC records. A remote attacker can cause the resolver to process excessive invalid DNSSEC cryptographic material to cause a denial of service.
6) Resource exhaustion (CVE-ID: CVE-2026-75029)
CWE-ID: CWE-400 - Resource exhaustion
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper handling of duplicate singleton RDATA records in the named message parser when processing query responses. A remote attacker can send a query response containing multiple identical copies of a record that should exist only once to cause a denial of service.
7) Reachable assertion (CVE-ID: CVE-2026-76163)
CWE-ID: CWE-617 - Reachable Assertion
CVSSv4: 8.7 [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]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to a reachable assertion in BIND named TKEY query handling when processing a TKEY query. A remote attacker can send a TKEY query to cause a denial of service.
The issue occurs when the named.conf configuration file contains no global options block.
8) Insufficient verification of data authenticity (CVE-ID: CVE-2026-77119)
CWE-ID: CWE-345 - Insufficient Verification of Data Authenticity
CVSSv4: 8.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause DNS cache poisoning.
The vulnerability exists due to insufficient verification of data authenticity in BIND 9 NSEC3 insecure-referral proof validation when processing insecure-referral proofs. A remote attacker can provide a validly signed NSEC3 record from an unrelated sibling zone to cause DNS cache poisoning.
9) Input validation error (CVE-ID: CVE-2026-77692)
CWE-ID: CWE-20 - Improper input validation
CVSSv4: 8.7 [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]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper handling of cryptographically invalid SIG(0) records in named when processing crafted DNS-over-HTTPS requests. A remote attacker can send a crafted DNS-over-HTTPS request containing a cryptographically invalid SIG(0) record and prematurely close the transport connection to cause a denial of service.
10) Input validation error (CVE-ID: CVE-2026-80274)
CWE-ID: CWE-20 - Improper input validation
CVSSv4: 8.7 [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]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper validation of a NOQNAME proof in the BIND validating resolver when processing DNSSEC responses. A remote attacker can send a DNS response containing a valid wildcard answer and signed NSEC3 proof followed by an unsigned NSEC record at the same owner name to cause a denial of service.
The resolver must query a DNSSEC-signed authoritative zone.
11) Memory leak (CVE-ID: CVE-2026-81563)
CWE-ID: CWE-401 - Missing release of memory after effective lifetime
CVSSv4: 8.7 [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]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to a failure to properly deallocate internal resources in SVCB/HTTPS AliasMode additional-data processing when processing an SVCB/HTTPS AliasMode record that references 14 or more SVCB/HTTPS ServiceMode records. A remote attacker can cause the resolver to process such records to cause a denial of service.
Repeated exploitation is required to exhaust resources.
12) Resource exhaustion (CVE-ID: CVE-2026-81736)
CWE-ID: CWE-400 - Resource exhaustion
CVSSv4: 8.7 [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]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to inefficient resource consumption in the BIND resolver when querying the root of a cached tree of SVCB/HTTPS AliasMode records. A remote attacker can send a query for the root of the cached record tree to cause a denial of service.
Remediation
Install update from vendor's website.