SB20261103138 - Ubuntu update for bind9
Published: November 3, 2026
Breakdown by Severity
- Low
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- Critical
Description
This security bulletin contains information about 18 vulnerabilities.
1) 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.
2) Reachable assertion (CVE-ID: CVE-2026-97313)
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 by triggering an unexpected exit of a BIND server.
The vulnerability exists due to a reachable assertion in BIND's response policy zone (RPZ) query handling when processing a recursive query followed by a non-recursive query. A remote attacker can send a query with recursion desired (RD=1) followed by a query with recursion disabled (RD=0) to trigger an assertion failure and terminate the server.
The server must allow recursive queries and have at least two RPZ zones configured: one with the default setting of "recursive-only yes" and another with "recursive-only no".
3) Reachable assertion (CVE-ID: CVE-2026-96888)
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 by triggering unexpected termination of named.
The vulnerability exists due to a reachable assertion in the ISC BIND resolver when processing redirects with both a redirect zone and strict QNAME minimization configured. A remote attacker can send DNS queries that trigger the assertion failure to cause named to abort and exit, resulting in a denial of service.
4) Buffer overflow (CVE-ID: CVE-2026-94300)
CWE-ID: CWE-119 - Memory corruption
CVSSv4: 9.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service and potentially execute arbitrary code.
The vulnerability exists due to memory corruption in the GSS-TSIG message handling of ISC BIND's named process when concurrently processing replayed signed UDP messages. A remote attacker can capture and replay a previously signed UDP message while the negotiated TSIG key remains valid to cause the process to abort, and additionally send crafted queries to a zone under their control to potentially execute arbitrary code.
5) 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.
6) 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.
7) 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.
8) Input validation error (CVE-ID: CVE-2026-78301)
CWE-ID: CWE-20 - Improper input validation
CVSSv4: 5.9 [CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to cause BIND to return attacker-supplied DNS data.
The vulnerability exists due to improper input validation in the named zone database when loading a malformed zone containing an NS or DNAME node above its origin. A remote privileged user can insert a malformed zone to cause BIND to return attacker-supplied DNS data.
On servers that also provide recursion, BIND can follow the locally sourced zone cut and cache attacker-supplied records for names outside the configured zone. On purely authoritative servers, queries may return out-of-zone referrals without the AA flag.
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) 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.
11) 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.
12) 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.
13) Insufficient verification of data authenticity (CVE-ID: CVE-2026-19941)
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 poison the DNS cache.
The vulnerability exists due to insufficient verification of data authenticity in the checkwildcard() function of the named resolver when validating wildcard-nonexistence proofs. A remote attacker can provide an out-of-zone NSEC record as proof that a wildcard does not exist to poison the DNS cache.
Exploitation requires control at the same or an upstream level of the zone name.
14) 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.
15) 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.
16) 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.
17) 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.
18) Allocation of Resources Without Limits or Throttling (CVE-ID: CVE-2026-19630)
CWE-ID: CWE-770 - Allocation of Resources Without Limits or Throttling
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 through CPU and/or memory exhaustion.
The vulnerability exists due to resource consumption without imposed limits in the BIND resolver's inbound DNS message processing when handling messages containing structures that trigger additional processing. A remote attacker can send a specially crafted DNS message containing a maliciously large number of these structures to exhaust CPU time and/or memory and cause a denial of service.
Remediation
Install update from vendor's website.