unbound: patch CVE-2026-42923

Details: https://nvd.nist.gov/vuln/detail/cve-2026-42923 Signed-off-by: Ankur Tyagi <ankur.tyagi85@gmail.com> Signed-off-by: Anuj Mittal <anuj.mittal@oss.qualcomm.com>
2026-09-23 11:21:11 +00:00 · 2026-09-15 10:13:54 +05:30
parent 11bc965378
commit 5d793b6ca9
2 changed files with 115 additions and 0 deletions
@@ -0,0 +1,114 @@
+From 7a2457c979cdc1f0c1bb1fe68010fdd2f46398f2 Mon Sep 17 00:00:00 2001
+From: "W.C.A. Wijngaards" <wouter@nlnetlabs.nl>
+Date: Wed, 20 May 2026 10:20:02 +0200
+Subject: [PATCH] - Fix CVE-2026-42923, Degradation of service with unbounded
+ NSEC3   hash calculations. Thanks to Qifan Zhang, Palo Alto Networks, for  
+ the report.
+
+(cherry picked from commit c343fff3a4de922835fec7232b90faed658b5371)
+
+CVE: CVE-2026-42923
+Upstream-Status: Backport [https://github.com/NLnetLabs/unbound/commit/c343fff3a4de922835fec7232b90faed658b5371]
+
+Dropped changes to the Changelog file.
+
+Signed-off-by: Ankur Tyagi <ankur.tyagi85@gmail.com>
+---
+ validator/val_neg.c   | 28 +++++++++++++++++++++++++++-
+ validator/val_nsec3.c |  5 -----
+ validator/val_nsec3.h |  6 ++++++
+ 3 files changed, 33 insertions(+), 6 deletions(-)
+
+diff --git a/validator/val_neg.c b/validator/val_neg.c
+index bc3a83aeb..0f2751121 100644
+--- a/validator/val_neg.c
+++ b/validator/val_neg.c
+@@ -62,6 +62,13 @@
+ #include "sldns/rrdef.h"
+ #include "sldns/sbuffer.h"
+ 
+/**
+ * The maximum salt length that the negative cache is willing to use.
+ * Larger salt increases the computation time, while recommendations are
+ * for zero salt length for zones.
+ */
+#define MAX_SALT_LENGTH 64
+
+ int val_neg_data_compare(const void* a, const void* b)
+ {
+ 	struct val_neg_data* x = (struct val_neg_data*)a;
+@@ -826,7 +833,11 @@ void neg_insert_data(struct val_neg_cache* neg,
+ 			(slen != 0 && zone->nsec3_salt && s
+ 			  && memcmp(zone->nsec3_salt, s, slen) != 0))) {
+ 
+-			if(slen > 0) {
+			if(slen > MAX_SALT_LENGTH) {
+				/* RFC 9276 s3.1: operators SHOULD NOT use a salt; large
+				 * salts inflate per-hash block count. Decline to cache. */
+				return;
+			} else if(slen > 0) {
+ 				uint8_t* sa = memdup(s, slen);
+ 				if(sa) {
+ 					free(zone->nsec3_salt);
+@@ -1169,6 +1180,15 @@ neg_find_nsec3_ce(struct val_neg_zone* zone, uint8_t* qname, size_t qname_len,
+ 	uint8_t hashce[NSEC3_SHA_LEN];
+ 	uint8_t b32[257];
+ 	size_t celen, b32len;
+	int hashmax = MAX_NSEC3_CALCULATIONS;
+	if(qlabs > hashmax) {
+		/* strip leading labels so the walk costs at most
+		 * MAX_NSEC3_CALCULATIONS hashes, mirroring val_nsec3.c */
+		while(qlabs > hashmax) {
+			dname_remove_label(&qname, &qname_len);
+			qlabs--;
+		}
+	}
+ 
+ 	*nclen = 0;
+ 	while(qlabs > 0) {
+@@ -1269,6 +1289,12 @@ neg_nsec3_proof_ds(struct val_neg_zone* zone, uint8_t* qname, size_t qname_len,
+ 	if(!zone->nsec3_hash) 
+ 		return NULL; /* not nsec3 zone */
+ 
+	if(!topname && qlabs > zone->labs + 1)
+		return NULL; /* iterator caller; opt-out proof would be discarded
+			     * at the !topname check below anyway.
+			     * The qlabs check allows the exact-match for
+			     * the one-label-below-zone case. */
+
+ 	if(!(data=neg_find_nsec3_ce(zone, qname, qname_len, qlabs, buf,
+ 		hashnc, &nclen))) {
+ 		return NULL;
+diff --git a/validator/val_nsec3.c b/validator/val_nsec3.c
+index 92d853825..62effde20 100644
+--- a/validator/val_nsec3.c
+++ b/validator/val_nsec3.c
+@@ -59,11 +59,6 @@
+ #include "sldns/sbuffer.h"
+ #include "util/config_file.h"
+ 
+-/**
+- * Max number of NSEC3 calculations at once, suspend query for later.
+- * 8 is low enough and allows for cases where multiple proofs are needed.
+- */
+-#define MAX_NSEC3_CALCULATIONS 8
+ /**
+  * When all allowed NSEC3 calculations at once resulted in error treat as
+  * bogus. NSEC3 hash errors are not cached and this helps breaks loops with
+diff --git a/validator/val_nsec3.h b/validator/val_nsec3.h
+index f668a270f..a13e92991 100644
+--- a/validator/val_nsec3.h
+++ b/validator/val_nsec3.h
+@@ -98,6 +98,12 @@ struct sldns_buffer;
+ /** The SHA1 hash algorithm for NSEC3 */
+ #define NSEC3_HASH_SHA1	0x01
+ 
+/**
+ * Max number of NSEC3 calculations at once, suspend query for later.
+ * 8 is low enough and allows for cases where multiple proofs are needed.
+ */
+#define MAX_NSEC3_CALCULATIONS 8
+
+ /**
+ * Cache table for NSEC3 hashes.
+ * It keeps a *pointer* to the region its items are allocated.
@@ -19,6 +19,7 @@ SRC_URI = "git://github.com/NLnetLabs/unbound.git;protocol=https;branch=master;t
           file://CVE-2026-40622.patch \
           file://CVE-2026-41292.patch \
           file://CVE-2026-42534.patch \
+           file://CVE-2026-42923.patch \
           "

 SRCREV = "f6269baa605d31859f28770e01a24e3677e5f82c"