# net: tun: bound receive headroom

CVE record · `CVE-2026-81000`

- **Identifiers:** `CVE-2026-81000`
- **State:** Confirmed
- **Severity:** CVSS 7.8 High
- **Critical:** No
- **CNA:** Linux
- **Technologies:** [Linux kernel](https://agentprime.io/advisories/technology/linux-kernel.md)
- **Published:** 11 Sept 2026
- **Updated:** 19 Oct 2026
- **Reviewed by a person:** No

Published by the CVE Program (CNA: Linux) at 11 Sept 2026, 19:42 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

## Affected products, as the CNA wrote them

- Vendor: Linux. Product: Linux.
  - affected: `eaea34b23c46bf17b4a5638be69ab3561854f34b to before ad715e713610d2d5473c3a6498c825ccecf26491` (git)
  - affected: `eaea34b23c46bf17b4a5638be69ab3561854f34b to before 708e87937de93f445225c134a2e20519f9b4ce60` (git)
  - affected: `eaea34b23c46bf17b4a5638be69ab3561854f34b to before 18ef24cdb2eba32e38f1d27f2d02b7b4212e8f76` (git)
  - affected: `eaea34b23c46bf17b4a5638be69ab3561854f34b to before 010eee265d6bd8769b6a523d2a0693d9b3f5df43` (git)
  - affected: `eaea34b23c46bf17b4a5638be69ab3561854f34b to before 379d85c7f25f3e05a428225e6b8a65613c6e9b9d` (git)
  - affected: `eaea34b23c46bf17b4a5638be69ab3561854f34b to before e098d9cc8859614a7f7baebc96e32a5a16b18ed2` (git)
  - affected: `eaea34b23c46bf17b4a5638be69ab3561854f34b to before 0ada54ea63e48b9c1608e917ccb7dfadbe86db28` (git)
  - affected: `eaea34b23c46bf17b4a5638be69ab3561854f34b to before 447c9303942c439a117d9b76ce6d6e2116b38ee7` (git)
  - Other versions: unaffected
- Vendor: Linux. Product: Linux.
  - affected: `4.6`
  - unaffected: `before 4.6` (semver)
  - unaffected: `5.10.270 to 5.10.*, inclusive` (semver)
  - unaffected: `5.15.221 to 5.15.*, inclusive` (semver)
  - unaffected: `6.1.188 to 6.1.*, inclusive` (semver)
  - unaffected: `6.6.157 to 6.6.*, inclusive` (semver)
  - unaffected: `6.12.109 to 6.12.*, inclusive` (semver)
  - unaffected: `6.18.50 to 6.18.*, inclusive` (semver)
  - unaffected: `7.2.4 to 7.2.*, inclusive` (semver)
  - unaffected: `7.3 to *, inclusive` (original_commit_for_fix)
  - Other versions: affected

## Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

## Severity and exploitation

- 7.8 High, CVSS 3.1: `CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`, from CNA (Linux)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0036, the 29th percentile, on 14 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

This record came from the full history of the CVE Program, published 11 Sept 2026. New records show when each source confirmed them.

## Sources

- [CVE List: CVE-2026-81000](https://www.cve.org/CVERecord?id=CVE-2026-81000)
- [NVD: CVE-2026-81000](https://nvd.nist.gov/vuln/detail/CVE-2026-81000)

### References from the CNA

- <https://git.kernel.org/stable/c/ad715e713610d2d5473c3a6498c825ccecf26491>
- <https://git.kernel.org/stable/c/708e87937de93f445225c134a2e20519f9b4ce60>
- <https://git.kernel.org/stable/c/18ef24cdb2eba32e38f1d27f2d02b7b4212e8f76>
- <https://git.kernel.org/stable/c/010eee265d6bd8769b6a523d2a0693d9b3f5df43>
- <https://git.kernel.org/stable/c/379d85c7f25f3e05a428225e6b8a65613c6e9b9d>
- <https://git.kernel.org/stable/c/e098d9cc8859614a7f7baebc96e32a5a16b18ed2>
- <https://git.kernel.org/stable/c/0ada54ea63e48b9c1608e917ccb7dfadbe86db28>
- <https://git.kernel.org/stable/c/447c9303942c439a117d9b76ce6d6e2116b38ee7>

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.

## Check whether this affects you

This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it. Compare the affected versions above with what you run.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), `get_advisory` returns this record and `search_advisories` finds related ones. Setup: <https://agentprime.io/mcp.md>
- As JSON: <https://api.agentprime.io/v1/advisories/CVE-2026-81000>
- Everything that needs attention now: <https://agentprime.io/advisories/critical.md>

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The web page: <https://agentprime.io/advisories/CVE-2026-81000/>. Everything for agents: <https://agentprime.io/llms.txt>.