CVE-2026-98240 net: ip_tunnel: initialize `options_len` before referencing options
A local attacker can trigger a kernel panic via specific IP tunnel configuration commands, causing a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98240?
CVE-2026-98240 is a memory corruption vulnerability in Linux, published on 6 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
net: ip_tunnel: initialize `options_len` before referencing options
The following command triggers a kernel panic:
ip link add d0 type dummy; ip link set d0 up ip route add 10.30.0.0/16 \ encap ip id 300 geneve_opts 4660:66:11223344 dev d0
memcpy: detected buffer overflow: 4 byte write of buffer size 0 kernel BUG at lib/string_helpers.c:1044! ... ip_tun_parse_opts.part.0.cold+0x10/0x10 ip_tun_build_state+0x116/0x2a0
On kernels built with GCC 15+ and `CONFIG_FORTIFY_SOURCE`, the fortified `memcpy()` got 0 sized destination with request of 4 bytes length:
static int ip_tun_parse_opts_geneve(...) { ... attr = tb[LWTUNNEL_IP_OPT_GENEVE_DATA]; data_len = nla_len(attr); /* == 4 */
struct geneve_opt *opt = ip_tunnel_info_opts(info) + opts_len; memcpy(opt->opt_data, nla_data(attr), data_len); /* ^^^^^^^^^^^^^ 0 since options_len is assigned afterwards */
Fixed by initializing the counter before the options are referenced. Matching what `tunnel_key_opts_set()` already does.
Which versions are affected by CVE-2026-98240?
How do I fix CVE-2026-98240?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-98240 being exploited?
There is no known exploitation of CVE-2026-98240 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-98240, DEBIAN-CVE-2026-98240, GHSA-2fq7-gw6w-f3qv, UBUNTU-CVE-2026-98240.