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Infoblox NIOS product is vulnerable to CVE-2021-25220

Infoblox NIOS product is vulnerable to CVE-2021-25220


Mar 17, 2022Knowledge


Using DNS forwarders can result in incorrect responses being sent to clients.



On March 16th, 2022 ISC announced a new vulnerability, CVE-2021-25220.


When using forwarders, bogus NS records supplied by, or via, those forwarders may be cached and used by named if it needs to recurse for any reason, causing it to obtain and pass on potentially incorrect answers.


Some examples of configurations that are vulnerable:

  • Resolvers using per zone or global forwarding with forward first (forward first is the default).
  • Resolvers not using global forwarding, but with per-zone forwarding with either forward first (the default) or forward only.
  • Resolvers configured with global forwarding along with zone statements that disable forwarding for part of the DNS namespace.

Authoritative-only BIND 9 servers are not vulnerable to this flaw.


Please note that this issue is possible if an upstream forwarder has been compromised. If a forwarder is under the same administration, however, a malicious attack of this kind is significantly less probable.


This vulnerability mainly impacts environments where recursive servers point to external forwarders that are not well maintained or are maintained by malicious actors.


Program impacted: BIND


Severity: Medium


Exploitable: Remotely


CVSS Score: 6.8




Affected Versions

8.4.x, 8.5.x (not including 8.5.5), 8.6.x



The cache could become poisoned with incorrect records leading to queries being made to the wrong servers, which might also result in false information being returned to clients.



Modify the configuration to either remove all forwarding or all possibility of recursion.



Infoblox suggests following one of the following options to resolve this vulnerability:

  • Upgrade to a NIOS version that includes the fix. 8.5.5 contains the fix and is available now
  • Apply NIOS version-specific Hotfix (8.2.6 CC, 8.4.8, 8.5.2, 8.5.3, 8.5.4, 8.6.0, 8.6.1). All related files are attached to this case. However, we recommend only downloading the Hotfix Release Form, Hotfix, and Revert Hotfix specific to your NIOS version

Additional Notes
  • This fix changes the problematic behavior so that out-of-bailiwick NS records (i.e. records that are not specifically queried for), are not cached on the local resolver. This prevents the attack vector exploitable by this issue
  • If there is already an existing named Hotfix installed on a member, please reach out to Support to review compatibility before installing this new Hotfix. Please provide the output from CLI command show upgrade_history from at least one member in each grid that has the other named Hotfix already applied
  • The 8.5.2 CC Hotfix can be used for environments running 8.5.2 without CC Mode. That is to say that this Hotfix will work for environments running 8.5.2 without CC Mode

NIOS Version-Specific Hotfix Files (attached to this KB)

8.2.6 CC
File File Name
Hotfix Release Form 8.2.6_CC_Hotfix_Release_Form_NIOS-84098.pdf
Hotfix Hotfix-8-2-6-NIOS-84099-APPLY-464c584608c58c641ba627b3b574b239-Thu-Mar-10-10-52-10-2022.bin2
Revert Hotfix Hotfix-8-2-6-NIOS-84099-REVERT-a041bb9ef12c36f47aca3995d483bc29-Thu-Mar-10-10-51-07-2022.bin2

File File Name
Hotfix Release Form 8.4.8_Hotfix_Release_Form_NIOS-84098.pdf
Hotfix Hotfix-8-4-8-NIOS-84100-APPLY-25152a5fd474f08ee8f5b5fc384d70f0-Thu-Mar-10-06-16-21-2022.bin
Revert Hotfix Hotfix-8-4-8-NIOS-84100-REVERT-0017a2156b1053e03f749f6d6da5444b-Thu-Mar-10-06-17-22-2022.bin

8.5.2 CC
File File Name
Hotfix Release Form 8.5.2_CC_Hotfix_Release_Form_NIOS-84098.pdf
Hotfix Hotfix-NIOS-84101-8.5.2-409296-APPLY-f209840f2de567972df1e82c4280fa32-Thu-Mar-10-03-37-25-2022.bin2
Revert Hotfix Hotfix-NIOS-84101-8.5.2-409296-REVERT-ded8e22609880e21a9b28221a08d59d5-Thu-Mar-10-03-38-25-2022.bin2

File File Name
Hotfix Release Form 8.5.3_Hotfix_Release_Form_NIOS-84098.pdf
Hotfix Hotfix-8.5.3-417434-NIOS-84102-APPLY-bfe82ed486ef1128b7f101459ce6045b-Thu-Mar-10-10-54-29-2022.bin
Revert Hotfix Hotfix-8.5.3-417434-NIOS-84102-REVERT-0b743b67031b640d5f4d32b0256fa2b5-Thu-Mar-10-10-55-30-2022.bin

File File Name
Hotfix Release Form 8.5.4_Hotfix_Release_Form_NIOS-84098.pdf
Hotfix Hotfix-NIOS-84103-8.5.4-419474-APPLY-a29ee7ffc0e2882d71fcd7c7a67c7e9b-Thu-Mar-10-03-39-29-2022.bin
Revert Hotfix Hotfix-NIOS-84103-8.5.4-419474-REVERT-c9c5d66a4a6bb29fdaa05d046e556ec4-Thu-Mar-10-03-40-30-2022.bin

File File Name
Hotfix Release Form 8.6.1_Hotfix_Release_Form_NIOS-84098.pdf
Hotfix Hotfix-8-6-1-NIOS-84105-APPLY-a13965711e22801a3e2ef2fe7d6c6d55-Thu-Mar-10-06-42-07-2022.bin
Revert Hotfix Hotfix-8-6-1-NIOS-84105-REVERT-ae656eedbb0f17fd8c6c3951a5ad40b5-Thu-Mar-10-03-48-34-2022.bin

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