From e614003e0af184d59b3eb85658149c8bef2ed50e Mon Sep 17 00:00:00 2001 From: "Hugo SIMELIERE (Schneider Electric)" Date: Wed, 20 May 2026 14:29:06 +0200 Subject: [PATCH] dnsmasq: Fix CVE-2026-4892 Pick patch from [1] dnsmasq 2.90 debian bookworm pacthes. [1] https://sources.debian.org/src/dnsmasq/2.90-4~deb12u2/debian/patches/CVE-2026-4892.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-2026-4892.patch | 41 +++++++++++++++++++ 2 files changed, 42 insertions(+) create mode 100644 meta-networking/recipes-support/dnsmasq/files/CVE-2026-4892.patch diff --git a/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb b/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb index 0d20e10712..21411839c7 100644 --- a/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb +++ b/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb @@ -17,6 +17,7 @@ SRC_URI = "http://www.thekelleys.org.uk/dnsmasq/${@['archive/', ''][float(d.getV file://dnsmasq-noresolvconf.service \ file://dnsmasq-resolved.conf \ file://CVE-2026-4891.patch \ + file://CVE-2026-4892.patch \ " SRC_URI[sha256sum] = "8f6666b542403b5ee7ccce66ea73a4a51cf19dd49392aaccd37231a2c51b303b" diff --git a/meta-networking/recipes-support/dnsmasq/files/CVE-2026-4892.patch b/meta-networking/recipes-support/dnsmasq/files/CVE-2026-4892.patch new file mode 100644 index 0000000000..148694a13f --- /dev/null +++ b/meta-networking/recipes-support/dnsmasq/files/CVE-2026-4892.patch @@ -0,0 +1,41 @@ +From 2f029069825270a3b91eb5f50bb8477ed7f761d3 Mon Sep 17 00:00:00 2001 +From: Simon Kelley +Date: Wed, 25 Mar 2026 23:16:35 +0000 +Subject: [PATCH] Fix buffer overflow in helper.c with large CLIDs. + CVE-2026-4892 + +Bug reported bt Royce M + +Location: helper.c:265-270 +DHCPv6 CLIDs can be up to 65535 bytes. When --dhcp-script is configured, +the helper hex-encodes raw CLID bytes via sprintf("%.2x") into daemon->packet (5131 bytes). +A 1000-byte CLID writes ~3000 bytes. The helper process retains root privileges. + +Note: log6_packet() correctly caps CLID to 100 bytes for logging, but the helper code path was missed. + +CVE: CVE-2026-4892 +Upstream-Status: Backport [https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=10e6b5b83e80749cba7b090d7780b29f908f0571] + +Signed-off-by: Hugo SIMELIERE (Schneider Electric) +--- + src/helper.c | 4 ++-- + 1 file changed, 2 insertions(+), 2 deletions(-) + +diff --git a/src/helper.c b/src/helper.c +index b9da2259..3a31e618 100644 +--- a/src/helper.c ++++ b/src/helper.c +@@ -261,8 +261,8 @@ int create_helper(int event_fd, int err_fd, uid_t uid, gid_t gid, long max_fd) + data.hostname_len + data.ed_len + data.clid_len, 1)) + continue; + +- /* CLID into packet */ +- for (p = daemon->packet, i = 0; i < data.clid_len; i++) ++ /* CLID into packet: limit to 100 bytes to avoid overflowing buffer. */ ++ for (p = daemon->packet, i = 0; i < data.clid_len && i < 100; i++) + { + p += sprintf(p, "%.2x", buf[i]); + if (i != data.clid_len - 1) +-- +2.43.0 +