diff --git a/unbound-1.25.1-CVE-2026-42959.patch b/unbound-1.25.1-CVE-2026-42959.patch
new file mode 100644
index 0000000..f500835
--- /dev/null
+++ b/unbound-1.25.1-CVE-2026-42959.patch
@@ -0,0 +1,17 @@
+diff --git a/unbound-1.24.2/validator/val_utils.c b/unbound-1.24.2/validator/val_utils.c
+index 549264d..4495695 100644
+--- a/unbound-1.24.2/validator/val_utils.c
++++ b/unbound-1.24.2/validator/val_utils.c
+@@ -1066,10 +1066,10 @@ val_fill_reply(struct reply_info* chase, struct reply_info* orig,
+ 			if(query_dname_compare(name, 
+ 				orig->rrsets[i]->rk.dname) == 0)
+ 			    chase->rrsets[chase->an_numrrsets
+-				+orig->ns_numrrsets+chase->ar_numrrsets++] 
++				+chase->ns_numrrsets+chase->ar_numrrsets++]
+ 				= orig->rrsets[i];
+ 		} else if(rrset_has_signer(orig->rrsets[i], name, len)) {
+-			chase->rrsets[chase->an_numrrsets+orig->ns_numrrsets+
++			chase->rrsets[chase->an_numrrsets+chase->ns_numrrsets+
+ 				chase->ar_numrrsets++] = orig->rrsets[i];
+ 		}
+ 	}
diff --git a/unbound.spec b/unbound.spec
index f86be70..ae305c6 100644
--- a/unbound.spec
+++ b/unbound.spec
@@ -80,6 +80,8 @@ Patch6: unbound-1.23.1-CVE-2025-5994.patch
 Patch7: unbound-1.20-unbound-anchor-key-38696.patch
 # https://nlnetlabs.nl/downloads/unbound/patch_CVE-2026-42944.diff
 Patch8: unbound-1.25.1-CVE-2026-42944.patch
+# https://nlnetlabs.nl/downloads/unbound/patch_CVE-2026-42959.diff
+Patch9: unbound-1.25.1-CVE-2026-42959.patch
 
 
 BuildRequires: gdb
@@ -188,6 +190,7 @@ pushd %{pkgname}
 %patch6 -p2 -b .CVE-2025-5994
 %patch7 -p2 -b .dnssec-ta-2024
 %patch8 -p2 -b .CVE-2026-42944
+%patch9 -p2 -b .CVE-2026-42959
 
 # copy common doc files - after here, since it may be patched
 cp -pr doc pythonmod libunbound ../
@@ -456,6 +459,7 @@ popd
 %changelog
 * Mon May 25 2026 Fedor Vorobev <fvorobev@redhat.com> - 1.16.2-5.11
 - Fix CVE-2026-42944 (RHEL‑177909)
+- Fix CVE-2026-42959 (RHEL-177809)
 
 * Tue Nov 11 2025 Petr Menšík <pemensik@redhat.com> - 1.16.2-5.10
 - Add new root key 38696 (RHEL-131172)