new file mode 100644
@@ -0,0 +1,72 @@
+From 2a514d577f035b1473d34201290be4394c732ff7 Mon Sep 17 00:00:00 2001
+From: "W.C.A. Wijngaards" <wouter@nlnetlabs.nl>
+Date: Wed, 22 Jul 2026 10:15:02 +0200
+Subject: [PATCH] - Fix CVE-2026-50251, Attacker supplied `0.0.0.0`/`::` glue
+ triggers defensive full-cache flush. Thanks to Qifan Zhang, Palo Alto
+ Networks, for the report.
+
+(cherry picked from commit e180b06298d8d39a764d3c5d4d4aca472c3a97d7)
+
+CVE: CVE-2026-50251
+Upstream-Status: Backport [https://github.com/NLnetLabs/unbound/commit/e180b06298d8d39a764d3c5d4d4aca472c3a97d7]
+
+Signed-off-by: Ankur Tyagi <ankur.tyagi85@gmail.com>
+---
+ doc/unbound.conf.rst | 7 +++++++
+ iterator/iter_donotq.c | 12 ++++++++++++
+ testdata/dns_error_reporting.rpl | 1 +
+ 3 files changed, 20 insertions(+)
+
+diff --git a/doc/unbound.conf.rst b/doc/unbound.conf.rst
+index d83816c6f..ca96a4411 100644
+--- a/doc/unbound.conf.rst
++++ b/doc/unbound.conf.rst
+@@ -1954,6 +1954,13 @@ These options are part of the **server:** clause.
+ flushing away any poison.
+ A value of 10 million is suggested.
+
++ It is useful to add 0.0.0.0/8 and '::' to the
++ :ref:`do-not-query-address<unbound.conf.do-not-query-address>` list.
++ Otherwise they may be answered, from localhost, and the different source
++ makes an unwanted reply that unnecessarily ticks up.
++ The :ref:`do-not-query-localhost<unbound.conf.do-not-query-localhost>`
++ option includes them, the zero subnets, when it is enabled.
++
+ Default: 0 (disabled)
+
+
+diff --git a/iterator/iter_donotq.c b/iterator/iter_donotq.c
+index 40ffb45c4..7eecf1354 100644
+--- a/iterator/iter_donotq.c
++++ b/iterator/iter_donotq.c
+@@ -132,6 +132,18 @@ donotq_apply_cfg(struct iter_donotq* dq, struct config_file* cfg)
+ if(cfg->do_ip6) {
+ if(!donotq_str_cfg(dq, "::1"))
+ return 0;
++ if(!donotq_str_cfg(dq, "::ffff:127.0.0.0/104"))
++ return 0;
++ }
++ /* RFC 1122 3.2.1.3 / RFC 6890 / RFC 4291 2.5.2: not valid as
++ * destination; on Linux these route to the local host. */
++ if(!donotq_str_cfg(dq, "0.0.0.0/8"))
++ return 0;
++ if(cfg->do_ip6) {
++ if(!donotq_str_cfg(dq, "::"))
++ return 0;
++ if(!donotq_str_cfg(dq, "::ffff:0:0/96"))
++ return 0;
+ }
+ }
+ addr_tree_init_parents(&dq->tree);
+diff --git a/testdata/dns_error_reporting.rpl b/testdata/dns_error_reporting.rpl
+index f1fac12a2..22175cade 100644
+--- a/testdata/dns_error_reporting.rpl
++++ b/testdata/dns_error_reporting.rpl
+@@ -12,6 +12,7 @@ server:
+ ede: no # It is not needed for dns-error-reporting; only for clients to receive EDEs
+ dns-error-reporting: yes
+ do-ip6: no
++ do-not-query-localhost: no
+
+ stub-zone:
+ name: domain
@@ -32,6 +32,7 @@ SRC_URI = "git://github.com/NLnetLabs/unbound.git;protocol=https;branch=master;t
file://CVE-2026-50046.patch \
file://CVE-2026-50243.patch \
file://CVE-2026-50248.patch \
+ file://CVE-2026-50251.patch \
"
SRCREV = "f6269baa605d31859f28770e01a24e3677e5f82c"