From 7dda8e9bd75855300f55faa2d803deebac226d43 Mon Sep 17 00:00:00 2001 From: "Hugo SIMELIERE (Schneider Electric)" Date: Wed, 20 May 2026 14:29:07 +0200 Subject: [PATCH] dnsmasq: Fix CVE-2026-4893 Pick patch from [1] dnsmasq 2.90 debian bookworm pacthes. [1] https://sources.debian.org/src/dnsmasq/2.90-4~deb12u2/debian/patches/CVE-2026-4893.patch Signed-off-by: Hugo SIMELIERE (Schneider Electric) Reviewed-by: Bruno VERNAY Signed-off-by: Anuj Mittal --- .../recipes-support/dnsmasq/dnsmasq_2.90.bb | 1 + .../dnsmasq/files/CVE-2026-4893.patch | 38 +++++++++++++++++++ 2 files changed, 39 insertions(+) create mode 100644 meta-networking/recipes-support/dnsmasq/files/CVE-2026-4893.patch diff --git a/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb b/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb index 21411839c7..4e548f6e59 100644 --- a/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb +++ b/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb @@ -18,6 +18,7 @@ SRC_URI = "http://www.thekelleys.org.uk/dnsmasq/${@['archive/', ''][float(d.getV file://dnsmasq-resolved.conf \ file://CVE-2026-4891.patch \ file://CVE-2026-4892.patch \ + file://CVE-2026-4893.patch \ " SRC_URI[sha256sum] = "8f6666b542403b5ee7ccce66ea73a4a51cf19dd49392aaccd37231a2c51b303b" diff --git a/meta-networking/recipes-support/dnsmasq/files/CVE-2026-4893.patch b/meta-networking/recipes-support/dnsmasq/files/CVE-2026-4893.patch new file mode 100644 index 0000000000..8aea321329 --- /dev/null +++ b/meta-networking/recipes-support/dnsmasq/files/CVE-2026-4893.patch @@ -0,0 +1,38 @@ +From 262aadd7a38947d2299234c8c9cf736ff6ad955d Mon Sep 17 00:00:00 2001 +From: Simon Kelley +Date: Wed, 25 Mar 2026 23:22:37 +0000 +Subject: [PATCH] Fix broken client subnet validation. CVE-2026-4893 + +Bug report from Royce M + +Location: forward.c:713, edns0.c:421 + +With --add-subnet enabled, process_reply() passes the OPT record +length (~23 bytes) instead of the packet length to check_source(). +All internal bounds checks fail, and the function always returns 1. +ECS source validation per RFC 7871 Section 9.2 is completely bypassed. + +CVE: CVE-2026-4893 +Upstream-Status: Backport [https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=e3a26d092e47bf1d18aeadb758e4ca35c83b5f2d] + +Signed-off-by: Hugo SIMELIERE (Schneider Electric) +--- + src/forward.c | 2 +- + 1 file changed, 1 insertion(+), 1 deletion(-) + +diff --git a/src/forward.c b/src/forward.c +index 32f37e40..19ff4401 100644 +--- a/src/forward.c ++++ b/src/forward.c +@@ -710,7 +710,7 @@ static size_t process_reply(struct dns_header *header, time_t now, struct server + /* Get extended RCODE. */ + rcode |= sizep[2] << 4; + +- if (option_bool(OPT_CLIENT_SUBNET) && !check_source(header, plen, pheader, query_source)) ++ if (option_bool(OPT_CLIENT_SUBNET) && !check_source(header, n, pheader, query_source)) + { + my_syslog(LOG_WARNING, _("discarding DNS reply: subnet option mismatch")); + return 0; +-- +2.43.0 +