Use-after-free in dnsdist - CVE-2026-27854
Published: April 23, 2026
Vulnerability identifier: #VU126959
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-27854
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: PowerDNS.COM B.V.
Affected software:
dnsdist
dnsdist
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to a use-after-free in EDNS option parsing via DNSQuestion:getEDNSOptions in custom Lua code when processing crafted DNS queries. A remote attacker can send crafted DNS queries to cause a denial of service.
The issue occurs in very specific setups where custom Lua code uses DNSQuestion:getEDNSOptions, and the vulnerable reference can point to a modified version of the DNS packet.
How to mitigate CVE-2026-27854
Install security update from vendor's website.