CVE-2025-40780Network attack vector

Cache poisoning due to weak PRNG

Published Oct 22, 2025 · Updated Oct 22, 2025

Predictable randomness in affected ISC BIND 9 releases through 9.21.12 allows remote attackers to poison resolver caches via spoofed responses. The outbound-query PRNG yields source ports and DNS query IDs that can be predicted; ISC has not disclosed the state or circumstances exposing its output. Exploitation requires successful response spoofing against a resolver; ISC reports that authoritative services are believed unaffected.

CVSS severity8.6
High
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Predictable randomness in affected ISC BIND 9 releases through 9.21.12 allows remote attackers to poison resolver caches via spoofed responses. The outbound-query PRNG yields source ports and DNS query IDs that can be predicted; ISC has not disclosed the state or circumstances exposing its output. Exploitation requires successful response spoofing against a resolver; ISC reports that authoritative services are believed unaffected.

The record

CVE
CVE-2025-40780
Published
Oct 22, 2025
Updated
Oct 22, 2025
Vendor
Internet Systems Consortium
Product
BIND 9
Classifications
CWE-341, T1565.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 22, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 22, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=9.16.0 <=9.16.50
  2. Affected versionversion=9.16.8-S1 <=9.16.50-S1
  3. Affected versionversion=9.18.0 <=9.18.39
  4. Affected versionversion=9.18.11-S1 <=9.18.39-S1
  5. Affected versionversion=9.20.0 <=9.20.13
  6. Affected versionversion=9.20.9-S1 <=9.20.13-S1
  7. Affected versionversion=9.21.0 <=9.21.12

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Internet Systems Consortium · BIND 9version=9.16.0 <=9.16.50; version=9.16.8-S1 <=9.16.50-S1; version=9.18.0 <=9.18.39; version=9.18.11-S1 <=9.18.39-S1; version=9.20.0 <=9.20.13; version=9.20.9-S1 <=9.20.13-S1; version=9.21.0 <=9.21.12

Published CVSS scores

8.6Internet Systems ConsortiumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-341Predictable from Observable State
T1565.002Transmitted Data Manipulation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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