A stack use-after-return flaw in SIG(0) handling code may enable ACL bypass
CVE-2026-3591 is fixed in 6 products on 1 platform, first by DEBIAN-CVE-2026-3591, released March 25, 2026. It is not reported as exploited. Patch Radar priority: Routine.
A use-after-return vulnerability exists in the `named` server when handling DNS queries signed with SIG(0). Using a specially-crafted DNS request, an attacker may be able to cause an ACL to improperly (mis)match an IP address. In a default-allow ACL (denying only specific IP addresses), this may lead to unauthorized access. Default-deny ACLs should fail-secure. This issue affects BIND 9 versions 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, and 9.20.9-S1 through 9.20.20-S1. BIND 9 versions 9.18.0 through 9.18.46 and 9.18.11-S1 through 9.18.46-S1 are NOT affected.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| bind · opensuse-leap 16.0 | 9.20.21-160000.1.1 | OPENSUSE-SU-2026:20550-1 | Apr 16, 2026 |
| bind · sles 15.7 | 9.20.21-150700.3.18.1 | SUSE-SU-2026:1351-1 | Apr 15, 2026 |
| bind · sles 16.0 | 9.20.21-160000.1.1 | SUSE-SU-2026:21204-1 | Apr 16, 2026 |
| bind9 · Debian 13.5 (trixie) | 1:9.20.21-1~deb13u1 | DEBIAN-CVE-2026-3591 | Mar 25, 2026 |
| bind9 · Debian 14 | 1:9.20.21-1 | DEBIAN-CVE-2026-3591 | Mar 25, 2026 |
| bind9 · Ubuntu 25.10 (questing) | 1:9.20.11-1ubuntu2.2 | bind9 1:9.20.11-1ubuntu2.2 | Apr 15, 2026 |
| bind9-dnsutils · Ubuntu 25.10 (questing) | 1:9.20.11-1ubuntu2.2 | bind9-dnsutils 1:9.20.11-1ubuntu2.2 | Apr 15, 2026 |
| bind9-host · Ubuntu 25.10 (questing) | 1:9.20.11-1ubuntu2.2 | bind9-host 1:9.20.11-1ubuntu2.2 | Apr 15, 2026 |
| bind9-libs · Ubuntu 25.10 (questing) | 1:9.20.11-1ubuntu2.2 | bind9-libs 1:9.20.11-1ubuntu2.2 | Apr 15, 2026 |
| bind9-utils · Ubuntu 25.10 (questing) | 1:9.20.11-1ubuntu2.2 | bind9-utils 1:9.20.11-1ubuntu2.2 | Apr 15, 2026 |
Patch Radar data is free to use with attribution. Terms and how to credit it.
Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.