CVE-2026-3593 Heap use-after-free vulnerability in BIND 9 DNS-over-HTTPS implementation
Attackers can exploit a use-after-free flaw in BIND 9's DNS-over-HTTPS feature to execute arbitrary code or cause denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-3593?
CVE-2026-3593 is a high-severity use after free vulnerability in Isc Bind, published on 20 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A use-after-free vulnerability exists within the DNS-over-HTTPS implementation. This issue affects BIND 9 versions 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, and 9.20.9-S1 through 9.20.22-S1. BIND 9 versions 9.18.0 through 9.18.48 and 9.18.11-S1 through 9.18.48-S1 are NOT affected.
Which versions are affected by CVE-2026-3593?
It affects 1 product.
Linux distribution packages (1)
bind openSUSE:Tumbleweed | All versions | 9.20.23-2.1 |
Products include Isc Bind.
How do I fix CVE-2026-3593?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-3593 being exploited?
There is no known exploitation of CVE-2026-3593 in the wild and no public exploit code.
Other vulnerabilities in Isc Bind
Sources
Also known as ALPINE-CVE-2026-3593, AZL-87093, BELL-CVE-2026-3593, DEBIAN-CVE-2026-3593, ECHO-f320-5f3f-a5ac, GHSA-8v2c-7qqj-7wp7 and 3 more.