VulnerabilityPublished 22 Oct 2025Updated 26 Feb 2026

CVE-2025-40778: ISC BIND 9 · Acceptance of Extraneous Untrusted Data With Trusted Data

Affects ISC BIND 9Source CVE Database V5

Not known to be exploited · CVSS 8.6 High.

Data as of 26 Oct 2026, 12:55 UTC

CVSS 3.1 base score

8.6High

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

EPSS: 0.6% chance of exploitation in 30 days – higher than 51% 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:C/C:N/I:H/A:N

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

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: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 22 Oct 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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
GitHubisc/bind`pkg:github/isc/bind`Other threats	Affected >=9.11.0 <=9.16.50 9.18.0 <=9.18.39 9.20.0 <=9.20.13 9.21.0 <=9.21.12	Fixed in–

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

AI-suggested

Organizations should monitor ISC advisories closely and apply official patches or updates for BIND 9 as soon as they become available. In the interim, administrators can implement strict DNS response validation policies, such as enabling DNSSEC validation to detect and reject forged records. Restricting recursive DNS queries to trusted clients and limiting exposure of DNS servers to untrusted networks can reduce attack vectors. Network-level protections like firewall rules and intrusion detection systems should be tuned to detect anomalous DNS traffic patterns. Regularly auditing DNS server configurations and logs for suspicious activity can help identify exploitation attempts early. Additionally, deploying redundant DNS infrastructure with diverse software versions can mitigate single points of failure due to this vulnerability.

Description

Under certain circumstances, BIND is too lenient when accepting records from answers, allowing an attacker to inject forged data into the cache. This issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.39, 9.20.0 through 9.20.13, 9.21.0 through 9.21.12, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.39-S1, and 9.20.9-S1 through 9.20.13-S1.

Impact

The primary impact of CVE-2025-40778 is the compromise of DNS data integrity through cache poisoning, which can redirect users to malicious websites, facilitate phishing, malware distribution, or man-in-the-middle attacks. Organizations relying on affected BIND versions risk undermining trust in their DNS infrastructure, potentially leading to data breaches, credential theft, or service disruption. Because DNS is foundational to internet and intranet operations, this vulnerability can affect a wide range of sectors including finance, government, telecommunications, and critical infrastructure. The lack of required privileges and user interaction makes exploitation feasible for remote attackers, increasing the threat surface. Although availability and confidentiality impacts are not directly indicated, the integrity breach alone can cascade into significant operational and security consequences globally.

Summary

CVE-2025-40778 is a vulnerability classified under CWE-349 (Acceptance of Extraneous Untrusted Data With Trusted Data) affecting ISC BIND 9 DNS server versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.39, 9.20.0 through 9.20.13, 9.21.0 through 9.21.12, and their S1 variants. The issue arises because BIND's DNS resolver is overly permissive when processing DNS response records, allowing attackers to inject forged DNS resource records into the cache alongside legitimate data. This cache poisoning can cause the DNS server to return malicious or incorrect DNS responses to clients, undermining the integrity of DNS resolution. The vulnerability can be exploited remotely without authentication or user interaction, leveraging network access to the vulnerable DNS server. The CVSS v3.1 base score is 8.6, reflecting high severity due to the ease of exploitation, lack of required privileges, and the potential for widespread impact on DNS integrity. No patches or exploit code are currently publicly available, but the vulnerability has been officially published and reserved since April 2025. The flaw affects a broad range of BIND 9 versions widely deployed in enterprise and ISP DNS infrastructure worldwide.

CWE-349Acceptance of Extraneous Untrusted Data With Trusted Data (opens in a new tab)
Base weakness
The product, when processing trusted data, accepts any untrusted data that is also included with the trusted data, treating the untrusted data as if it were trusted.
OWASP Cheat Sheets
XML Security (opens in a new tab)
REST Security (opens in a new tab)
JSON Web Token for Java (opens in a new tab)
REST Assessment (opens in a new tab)
Cross-Site Request Forgery Prevention (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.2 (opens in a new tab)
V3.5.3 (opens in a new tab)
V13.2.6 (opens in a new tab)
Attack patterns
Cache Poisoning (opens in a new tab)
DNS Cache Poisoning (opens in a new tab)
Manipulating Writeable Configuration Files (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 27 Feb 2026, 05:08 UTC

WeaknessesCWE-349

Technical details

References

Community reviews

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