VulnerabilityPublished 16 Sep 2026Updated 17 Sep 2026

CVE-2026-75029: ISC BIND 9 · Asymmetric Resource Consumption

Affects ISC BIND 9Source CVE Database V5

Compare

Not known to be exploited · CVSS 5.3 Medium.

Data as of 31 Oct 2026, 20:20 UTC

CVSS 3.1 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 16 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 31 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
ISCBIND 9	Affected >=9.11.0 <=9.18.50 >=9.20.0 <=9.20.27 >=9.21.0 <=9.21.25 >=9.11.3-S1 <=9.18.50-S1 >=9.20.9-S1 <=9.20.27-S1	Fixed in–
GitHubisc/bind9`pkg:github/isc/bind9`Other threats	Affected >=9.11.0 <=9.18.50 >=9.20.0 <=9.20.27 >=9.21.0 <=9.21.25 >=9.11.3-S1 <=9.18.50-S1 >=9.20.9-S1 <=9.20.27-S1	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Until an official fix is available, consider monitoring memory usage patterns for unusual spikes related to DNS query responses. No vendor advisory or patch links are provided in the current data.

Description

CVE-2026-75029 is a medium severity vulnerability in ISC BIND 9 that allows an attacker to cause asymmetric resource consumption via amplification. By sending multiple copies of a record that should only exist once in a query response, such as an SOA record with identical RDATA, the BIND server appends these to the in-memory RDATA set. This behavior increases memory usage of the negative cache and may lead to other memory-related attack vectors. The vulnerability affects multiple BIND 9 versions from 9.11.0 through 9.21.25 and their respective S1 variants.

Impact

The vulnerability can cause increased memory usage in the affected BIND 9 servers, specifically in the negative cache, which may degrade service availability or lead to denial of service conditions. There is no impact on confidentiality or integrity reported. No known exploits are currently in the wild.

Summary

This vulnerability involves ISC BIND 9's handling of DNS query responses where an attacker can send multiple copies of a record that should be unique, like an SOA record. When the RDATA is identical across these copies, BIND appends the record repeatedly to the in-memory RDATA set. This results in increased memory consumption in the negative cache, potentially leading to memory exhaustion or other memory-based attacks. The issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, and their S1 variants within these ranges.

CWE-405Asymmetric Resource Consumption (Amplification) (opens in a new tab)
Class weakness
The product does not properly control situations in which an adversary can cause the product to consume or produce excessive resources without requiring the adversary to invest equivalent work or otherwise prove authorization, i.e., the adversary's influence is "asymmetric."
Architecture and Design
An application must make resources available to a client commensurate with the client's access level.
Architecture and Design
An application must, at all times, keep track of allocated resources and meter their usage appropriately.
System Configuration
Consider disabling resource-intensive algorithms on the server side, such as Diffie-Hellman key exchange.
OWASP Cheat Sheets
File Upload (opens in a new tab)
OWASP ASVS 4.0.3
V12.1.1 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 17 Oct 2026, 23:46 UTC

WeaknessesCWE-405

Technical details

References

Community reviews

Related threats