From d9dfa7ccea2c4975a6a274268eef589dc602b44c Mon Sep 17 00:00:00 2001 From: "Benjamin Robin (Schneider Electric)" Date: Wed, 1 Jul 2026 14:08:45 +0200 Subject: [PATCH] dnsmasq: fix CVE-2026-2291 dnsmasqs extract_name() function can be abused to cause a heap buffer overflow, allowing an attacker to inject false DNS cache entries, which could result in DNS lookups to redirect to an attacker-controlled IP address, or to cause a DoS. This patch is used by debian bookworm (2.90-4_deb12u2). Signed-off-by: Benjamin Robin (Schneider Electric) Signed-off-by: Anuj Mittal --- .../recipes-support/dnsmasq/dnsmasq_2.90.bb | 1 + .../dnsmasq/files/CVE-2026-2291.patch | 40 +++++++++++++++++++ 2 files changed, 41 insertions(+) create mode 100644 meta-networking/recipes-support/dnsmasq/files/CVE-2026-2291.patch diff --git a/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb b/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb index 7830c9c81f..3a7af56c34 100644 --- a/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb +++ b/meta-networking/recipes-support/dnsmasq/dnsmasq_2.90.bb @@ -20,6 +20,7 @@ SRC_URI = "http://www.thekelleys.org.uk/dnsmasq/${@['archive/', ''][float(d.getV file://CVE-2026-4892.patch \ file://CVE-2026-4893.patch \ file://CVE-2026-5172.patch \ + file://CVE-2026-2291.patch \ " SRC_URI[sha256sum] = "8f6666b542403b5ee7ccce66ea73a4a51cf19dd49392aaccd37231a2c51b303b" diff --git a/meta-networking/recipes-support/dnsmasq/files/CVE-2026-2291.patch b/meta-networking/recipes-support/dnsmasq/files/CVE-2026-2291.patch new file mode 100644 index 0000000000..78545159d0 --- /dev/null +++ b/meta-networking/recipes-support/dnsmasq/files/CVE-2026-2291.patch @@ -0,0 +1,40 @@ +From c3059821cd52b423592aeffef7935fdf81035a81 Mon Sep 17 00:00:00 2001 +From: Simon Kelley +Date: Fri, 10 Apr 2026 16:29:31 +0100 +Subject: [PATCH] Fix buffer overflow in struct bigname. CVE-2026-2291 + +All buffers capable of holding a domain name should be +at least MAXDNAME*2 + 1 bytes long, where MAXDNAME is the maximum +size of a domain name. The accounts for the trailing zero and the +fact that some characters are escaped in the internal representation +of a domain name in dnsmasq. + +The declaration of struct bigname get this wrong, with the effect +that a remote attacker capable of asking DNS queries or answering DNS +queries can cause a large OOB write in the heap. + +This was first spotted by Andrew S. Fasano. + +CVE: CVE-2026-2291 +Upstream-Status: Backport [https://sources.debian.org/src/dnsmasq/2.90-4~deb12u2/debian/patches/CVE-2026-2291.patch] + +Signed-off-by: Benjamin Robin +--- + src/dnsmasq.h | 2 +- + 1 file changed, 1 insertion(+), 1 deletion(-) + +diff --git a/src/dnsmasq.h b/src/dnsmasq.h +index e455c3f7..be8cf2ad 100644 +--- a/src/dnsmasq.h ++++ b/src/dnsmasq.h +@@ -467,7 +467,7 @@ struct interface_name { + }; + + union bigname { +- char name[MAXDNAME]; ++ char name[(2*MAXDNAME) + 1]; + union bigname *next; /* freelist */ + }; + +-- +2.43.0