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ISC BIND 9 CVE-2026-10822

| EUVDEUVD-2026-47705 MEDIUM
Reachable Assertion (CWE-617)
2026-07-22 isc GHSA-42qr-f5rc-vfw9
6.5
CVSS 3.1 · Vendor: isc
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Severity by source

Vendor (isc) PRIMARY
6.5 MEDIUM
AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
vuln.today AI
6.5 MEDIUM

Network-reachable via DNS zone data; no privileges required to operate a malicious zone; UI:R reflects mandatory two-phase trigger; impact is availability-only crash with no data exposure.

3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
MEDIUM
qualitative
Red Hat
6.5 MEDIUM
qualitative

Primary rating from Vendor (isc).

CVSS VectorVendor: isc

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

2
Analysis Generated
Jul 22, 2026 - 15:16 vuln.today
CVE Published
Jul 22, 2026 - 14:09 cve.org
MEDIUM 6.5

DescriptionCVE.org

If BIND encounters a particular invalid data structure in a DNS record, it will accept the invalid data, and may subsequently abort and exit.

BIND will first need to store a DNS record for a key (KEY, DNSKEY, etc.). That key must specify a PRIVATEDNS algorithm (253), and in the algorithm identifier, improperly give a length longer than the actual identifier data. The invalid identifier will be stored. If BIND later needs to render that record to text, it will use the invalid length during processing, leading to a consistency check failing. This issue affects BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.18.11-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.

AnalysisAI

Availability loss in ISC BIND 9 DNS server arises when a stored DNS key record containing the PRIVATEDNS algorithm (algorithm number 253) carries a malformed identifier length field that exceeds the actual identifier data. BIND accepts the structurally invalid record without rejecting it at ingestion time, but when it subsequently attempts to render that record to text - during logging, zone display, or similar operations - the inconsistent length triggers a reachable assertion (CWE-617) that causes BIND to abort and exit. No active exploitation has been confirmed (not listed in CISA KEV) and no public exploit code has been identified at time of analysis; however, BIND 9 spans a very wide version range and is critical infrastructure, making patch urgency high despite the medium CVSS score of 6.5.

Technical ContextAI

BIND 9 (cpe:2.3:a:isc:bind_9:*:*:*:*:*:*:*:*) is ISC's reference DNS server implementation, widely used as both authoritative and recursive resolver. The vulnerability exploits the PRIVATEDNS algorithm identifier (algorithm number 253) defined in the DNS KEY/DNSKEY record format, which is reserved for private, vendor-specific algorithm extensions. The malformed record is one where the length field within the algorithm identifier claims to be longer than the bytes that actually follow it. BIND's zone data ingestion path accepts this malformed structure without performing a length consistency check. The defect class is CWE-617 (Reachable Assertion): a defensive consistency check exists in the text-rendering code path that compares expected length against actual data, but that check can only be reached after the invalid record is already stored, creating a deferred crash rather than an early rejection. The crash path is triggered on any code that serializes stored records to text - such as named-checkzone, rndc dumpdb, logging, or zone transfer output.

RemediationAI

Upgrade to BIND 9.20.26 (available at https://downloads.isc.org/isc/bind9/9.20.26) or BIND 9.21.24 (available at https://downloads.isc.org/isc/bind9/9.21.24) as the primary fix. Subscription S-BIND customers should consult the ISC advisory at https://kb.isc.org/docs/cve-2026-10822 for the corresponding fixed S-BIND release. If immediate patching is not feasible, a compensating control is to restrict which zones BIND accepts via zone transfer and to ensure that external, untrusted DNS data sources are not configured as zone masters or forwarders for authoritative BIND instances - this reduces the attacker's ability to introduce malformed records, though it does not eliminate risk for recursive resolvers. There is no configuration knob in BIND that disables text rendering of stored records without broadly reducing functionality, so patching is the only complete fix.

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise Desktop 15 SP7 SUSE Linux Enterprise Module for Basesystem 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP7 SUSE Linux Enterprise Server 15 SP7 SUSE Linux Enterprise Server for SAP Applications 15 SP7 Fixed
SUSE Linux Enterprise Module for Server Applications 15 SP7 Fixed
openSUSE Leap 16.0 Fixed
openSUSE Tumbleweed Fixed

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CVE-2026-10822 vulnerability details – vuln.today

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