A heap-based out-of-bounds write vulnerability in the DHCPv6 implementation of dnsmasq allows local attackers to execute arbitrary code with root privileges via a crafted DHCPv6 packet.
Reference: [ https://nvd.nist.gov/vuln/detail/CVE-2026-4892 ] Signed-off-by: Abhishek Bachiphale <[email protected]> --- .../recipes-support/dnsmasq/dnsmasq_2.92.bb | 1 + .../dnsmasq/files/CVE-2026-4892.patch | 36 +++++++++++++++++++ 2 files changed, 37 insertions(+) create mode 100644 meta-networking/recipes-support/dnsmasq/files/CVE-2026-4892.patch diff --git a/meta-networking/recipes-support/dnsmasq/dnsmasq_2.92.bb b/meta-networking/recipes-support/dnsmasq/dnsmasq_2.92.bb index 850bfd2657..cf900328ed 100644 --- a/meta-networking/recipes-support/dnsmasq/dnsmasq_2.92.bb +++ b/meta-networking/recipes-support/dnsmasq/dnsmasq_2.92.bb @@ -18,6 +18,7 @@ SRC_URI = "http://www.thekelleys.org.uk/dnsmasq/${@['archive/', ''][float(d.getV file://CVE-2026-2291.patch \ file://CVE-2026-4890.patch \ file://CVE-2026-4891.patch \ + file://CVE-2026-4892.patch \ " SRC_URI[sha256sum] = "fd908e79ff37f73234afcb6d3363f78353e768703d92abd8e3220ade6819b1e1" 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..01637601a3 --- /dev/null +++ b/meta-networking/recipes-support/dnsmasq/files/CVE-2026-4892.patch @@ -0,0 +1,36 @@ +commit 011a36c51438c986535a7248ed2e7f424f8e1078 +Author: Simon Kelley <[email protected]> +Date: Wed Mar 25 23:16:35 2026 +0000 + +Fix buffer overflow in helper.c with large CLIDs. CVE-2026-4892 + +Bug reported bt Royce M <[email protected]> + +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: Abhishek Bachiphale <[email protected]> + +diff --git a/src/helper.c b/src/helper.c +index 72f81fe..2c12801 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, RW_READ)) + 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) -- 2.40.0
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