Eglibc: Calling gethostbyaddr or gethostbyaddr_r with a configured nsswitch.conf that specifies the library's DNS backend in the GNU C Library version 2.34…
A vulnerability exists in the GNU C Library (eglibc) versions 2.34 through 2.43 where calling gethostbyaddr or gethostbyaddr_r with a nsswitch.conf specifying the library's DNS backend could cause the application to treat a non-answer DNS response section as a valid answer. This behavior violates the DNS specification and may lead to denial of service. The issue affects multiple specific Ubuntu package versions of eglibc. No known exploits are reported in the wild.
AI Analysis
Technical Summary
In GNU C Library versions 2.34 to 2.43, when gethostbyaddr or gethostbyaddr_r functions are called with a nsswitch.conf specifying the library's DNS backend, a crafted DNS response can cause the application to accept a non-answer DNS response section as a valid answer. This behavior violates DNS protocol specifications and can cause application instability or denial of service.
Potential Impact
The vulnerability does not affect confidentiality or integrity but can cause a denial of service (application crash or hang) due to improper handling of DNS responses. There are no known exploits in the wild.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, avoid using the affected gethostbyaddr or gethostbyaddr_r calls with the library's DNS backend configured in nsswitch.conf or apply any recommended workarounds from the vendor.
Eglibc: Calling gethostbyaddr or gethostbyaddr_r with a configured nsswitch.conf that specifies the library's DNS backend in the GNU C Library version 2.34…
Description
A vulnerability exists in the GNU C Library (eglibc) versions 2.34 through 2.43 where calling gethostbyaddr or gethostbyaddr_r with a nsswitch.conf specifying the library's DNS backend could cause the application to treat a non-answer DNS response section as a valid answer. This behavior violates the DNS specification and may lead to denial of service. The issue affects multiple specific Ubuntu package versions of eglibc. No known exploits are reported in the wild.
CVSS v3.1
Score 7.5high
Affected software
pkg:deb/ubuntu/[email protected]+esm4?arch=source&distro=esm-infra-legacy/trustypkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=questingRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
In GNU C Library versions 2.34 to 2.43, when gethostbyaddr or gethostbyaddr_r functions are called with a nsswitch.conf specifying the library's DNS backend, a crafted DNS response can cause the application to accept a non-answer DNS response section as a valid answer. This behavior violates DNS protocol specifications and can cause application instability or denial of service.
Potential Impact
The vulnerability does not affect confidentiality or integrity but can cause a denial of service (application crash or hang) due to improper handling of DNS responses. There are no known exploits in the wild.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, avoid using the affected gethostbyaddr or gethostbyaddr_r calls with the library's DNS backend configured in nsswitch.conf or apply any recommended workarounds from the vendor.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-4437
- Osv Schema Version
- 1.7.0
- Aliases
- []
- Ecosystems
- ["Ubuntu:Pro:14.04:LTS","Ubuntu:24.04:LTS","Ubuntu:25.10"]
- Database Specific Severity
- null
- Cvss Version
- 3.1
Threat ID: 6a6151239c2644c7f8da6230
Added to database: 07/22/2026, 23:24:19 UTC
Last enriched: 07/22/2026, 23:56:26 UTC
Last updated: 07/31/2026, 19:22:59 UTC
Views: 15
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