SB2026082816 - Fedora EPEL 10.2 update for nsd
Published: August 28, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 4 vulnerabilities.
1) Improper access control (CVE-ID: CVE-2026-18664)
CWE-ID: CWE-284 - Improper Access Control
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to bypass IP-based access control restrictions.
The vulnerability exists due to improper access control in IP range access control handling when comparing IP addresses against configured ranges on little endian systems. A remote attacker can send requests from unintended IP addresses to bypass IP-based access control restrictions.
The issue affects both IPv4 and IPv6 range comparisons.
2) Improper Resource Shutdown or Release (CVE-ID: CVE-2026-18916)
CWE-ID: CWE-404 - Improper Resource Shutdown or Release
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper handling of throttled tcp receive windows in serve child processing when handling a tcp query followed by a reduced tcp receive window. A remote attacker can throttle the tcp receive window down to 1 after sending a tcp query to cause a denial of service.
By repeatedly crashing serve child processes, all tcp service to the affected instance can be denied.
3) Input validation error (CVE-ID: CVE-2026-19401)
CWE-ID: CWE-20 - Improper input validation
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper input validation in the NSD server child process when handling specially crafted UDP DNS queries with multiple DNS Cookie options. A remote attacker can send a specially crafted query to cause a denial of service.
Only debugging or non-release builds are vulnerable, and sustained exploitation can severely hamper service or deny DNS service.
4) Improper access control (CVE-ID: CVE-2026-19538)
CWE-ID: CWE-284 - Improper Access Control
CVSSv4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to bypass IP-based access controls.
The vulnerability exists due to improper access control in the proxy protocol port handling when processing a repeated query over a kept-open TCP or TLS connection. A remote user can send the same query twice on a persistent connection to bypass IP-based access controls.
This issue affects BLOCKED access control list items and may allow spoofing of arbitrary IP addresses for queries, transfers, and notifies.
Remediation
Install update from vendor's website.