CVE-2026-4437
DNS Response Validation Bypass in GNU C Library gethostbyaddr Functions
Publication date: 2026-03-20
Last updated on: 2026-04-07
Assigner: GNU C Library
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| gnu | glibc | From 2.34 (inc) to 2.43 (inc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-125 | The product reads data past the end, or before the beginning, of the intended buffer. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability occurs in the GNU C Library versions 2.34 to 2.43 when the functions gethostbyaddr or gethostbyaddr_r are called with a configured nsswitch.conf that specifies the library's DNS backend. A crafted response from the configured DNS server can cause a violation of the DNS specification, leading the application to mistakenly treat a non-answer section of the DNS response as a valid answer.
How can this vulnerability impact me? :
The impact of this vulnerability is that an application relying on gethostbyaddr or gethostbyaddr_r may accept incorrect DNS responses as valid. This could potentially lead to incorrect hostname resolutions, which might affect application behavior, security decisions, or network communications.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
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What immediate steps should I take to mitigate this vulnerability?
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