CVE-2025-40780

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Important Important Impact What does this mean?
8.6 CVSS v3 Base Score

Description

A vulnerability was found in BIND resolvers caused by a weakness in the Pseudo Random Number Generator (PRNG). This weakness allows an attacker to potentially predict the source port and query ID used by BIND, enabling cache poisoning attacks. If successful, the attacker can inject malicious DNS responses into the resolver’s cache, causing clients to receive spoofed DNS data. Authoritative servers are generally unaffected, but recursive resolvers are exposed to this risk. Exploitation is remote and does not require user interaction.

Statement

This vulnerability in BIND 9 resolvers caused by a weakness in the Pseudo Random Number Generator (PRNG) used to select the UDP source port and DNS query (transaction) ID. Exploitation requires an attacker to correctly predict both values and race the legitimate authoritative response with a spoofed packet to perform cache poisoning. While the PRNG weakness reduces entropy and makes prediction feasible under certain conditions, this still requires precise timing, on-path or spoofing capabilities, and targeting of recursive resolvers.

The impact is limited to resolver cache integrity; it does not allow remote code execution, privilege escalation, or direct compromise of the BIND server itself. Authoritative servers are not affected. Additionally, operational mitigations such as DNSSEC validation, access control restricting recursion, and network-level packet filtering reduce real-world exploitability. No active exploits have been observed in the wild.

Because exploitation is non-trivial, requires network-level spoofing and precise timing, and only affects cache integrity without server compromise, the vulnerability is considered Important rather than Critical.

Mitigation

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

To reduce risk, restrict recursive queries to trusted or internal networks only, and apply rate limiting or firewall rules to prevent excessive or repetitive requests. Enabling DNSSEC validation helps reject forged records, while isolating recursive resolvers from authoritative servers limits the impact of potential cache poisoning. Active monitoring of CPU usage, query volume, and cache anomalies can provide early warning of abuse or attacks.

Additional Information

External References

Content from www.cve.org is not included.https://www.cve.org/CVERecord?id=CVE-2025-40780

Content from nvd.nist.gov is not included.https://nvd.nist.gov/vuln/detail/CVE-2025-40780

Affected Packages and Issued Red Hat Security Errata

Products / Services Components State Errata
Red Hat Discovery 2 discovery/discovery-ui-rhel9 Fixed RHSA-2025:21994
Red Hat Enterprise Linux 10 bind Fixed RHSA-2025:19912
Red Hat Enterprise Linux 10 bind Fixed RHSA-2025:21034
Red Hat Enterprise Linux 6 bind Not affected
Red Hat Enterprise Linux 7 bind Not affected
Red Hat Enterprise Linux 8 bind9.16 Fixed RHSA-2025:19793
Red Hat Enterprise Linux 8 bind Not affected
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support bind9.16 Fixed RHSA-2025:22168
Red Hat Enterprise Linux 8.6 Telecommunications Update Service bind9.16 Fixed RHSA-2025:22168
Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions bind9.16 Fixed RHSA-2025:22168
Unless explicitly stated as not affected, all previous versions of packages in any minor update stream of a product listed here should be assumed vulnerable, although may not have been subject to full analysis.

Common Vulnerability Scoring System (CVSS) Score Details

Important note

CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authorities (CNA) source for its products and services (see Red Hat classifications ).

CVSS v3 Score Breakdown Red Hat NVD
CVSS v3 Base Score 8.6
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Changed
Confidentiality Impact None
Integrity Impact High
Availability Impact None

CVSS v3 Vector

Red Hat CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N

Frequently Asked Questions

Why is Red Hat's CVSS v3 score or Impact different from other vendors?

 For open source software shipped by multiple vendors, the CVSS base scores may vary for each vendor's version depending on the version they ship, how they ship it, the platform, and even how the software is compiled. This makes scoring of vulnerabilities difficult for third-party vulnerability databases such as NVD that only provide a single CVSS base score for each vulnerability. Red Hat scores reflect how a vulnerability affects our products specifically.

For more information, see https://access.redhat.com/solutions/762393.

My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?
  • "Under investigation" doesn't necessarily mean that the product is affected by this vulnerability. It only means that our Analysis Team is still working on determining whether the product is affected and how it is affected.
  • "Affected" means that our Analysis Team has determined that this product is affected by this vulnerability and might release a fix to address this in the near future.

What can I do if my product is listed as "Will not fix"?

 A "will not fix" status means that a fix for an affected product version is not planned or not possible due to complexity, which may create additional risk.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Upgrade to a supported product version that includes a fix for this vulnerability (recommended).
  • Apply a mitigation (if one exists).
  • Open a This content is not included.support case to request a prioritization of releasing a fix for this vulnerability.

What can I do if my product is listed as "Fix deferred"?

 A deferred status means that a fix for an affected product version is not guaranteed due to higher-priority development work.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Apply a mitigation (if one exists).
  • Open a This content is not included.support case to request a prioritization of releasing a fix for this vulnerability.
  • Red Hat Engineering focuses on addressing high-priority issues based on their complexity or limited lifecycle support. Therefore, lower-priority issues will not receive immediate fixes.

What is a mitigation?

 A mitigation is an action that can be taken to reduce the impact of a security vulnerability, without deploying any fixes.

I have a Red Hat product but it is not in the above list, is it affected?

 The listed products were found to include one or more of the components that this vulnerability affects. These products underwent a thorough evaluation to determine their affectedness by this vulnerability. Note that layered products (such as container-based offerings) that consume affected components from any of the products listed in this table may be affected and are not represented.

Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?

 In order to maintain code stability and compatibility, Red Hat usually does not rebase packages to entirely new versions. Instead, we backport fixes and new features to an older version of the package we distribute. This can result in some security scanners that only consider the package version to report the package as vulnerable. To avoid this, we suggest that you use an approved vulnerability scanner from our This content is not included.Red Hat Vulnerability Scanner Certification program.

My product is listed as "Out of Support Scope". What does this mean?

 When a product is listed as "Out of Support Scope", it means a vulnerability with the impact level assigned to this CVE is no longer covered by its current support lifecycle phase. The product has been identified to contain the impacted component, but analysis to determine whether it is affected or not by this vulnerability was not performed. The product should be assumed to be affected. Customers are advised to apply any mitigation options documented on this page, consider removing or disabling the impacted component, or upgrade to a supported version of the product that has an update available.