# ipv6: fix possible infinite loop in fib6_select_path()

CVE record · `CVE-2026-63968`

- **Identifiers:** `CVE-2026-63968`
- **State:** Confirmed
- **Severity:** CVSS 7.5 High
- **Critical:** No
- **CNA:** Linux
- **Weakness (CWE):** [CWE-835](https://cwe.mitre.org/data/definitions/835.html)
- **Tags:** [Denial of service](https://agentprime.io/advisories/tag/dos.md)
- **Technologies:** [Linux kernel](https://agentprime.io/advisories/technology/linux-kernel.md)
- **Published:** 19 Jul 2026
- **Updated:** 19 Oct 2026
- **Reviewed by a person:** No

Published by the CVE Program (CNA: Linux) at 19 Jul 2026, 14:55 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: `d0ec61c9f3583b76aebdbb271f5c0d3fcccd48b2 to before 3948a7d92f7678e89e1776bb2d169afcad63b1ae` (git)
  - affected: `52da02521ede55fb86546c3fffd9377b3261b91f to before c87cd3cb309634bc8f50a54e2079424f219ac21f` (git)
  - affected: `34a949e7a0869dfa31a40416d2a56973fae1807b to before 0f7b73c3452635de83b8711b31abdda8e49aad7b` (git)
  - affected: `d9ccb18f83ea2bb654289b6ecf014fd267cc988b to before ab9a10969a907b472a0196d999c08ff7144172e3` (git)
  - affected: `d9ccb18f83ea2bb654289b6ecf014fd267cc988b to before 9b9d5bd6e3d4c9cecab5407604b690684b2532d2` (git)
  - affected: `d9ccb18f83ea2bb654289b6ecf014fd267cc988b to before 9c7da87c2dc860bb17ca1ece942495d28b1ce3b9` (git)
  - affected: `11edcd026012ac18acee0f1514db3ed1b160fc6f` (git)
  - affected: `6.1.128 to before 6.1.176` (semver)
  - affected: `6.6.75 to before 6.6.143` (semver)
  - affected: `6.12.2 to before 6.12.93` (semver)
  - affected: `6.11.11 to before 6.12` (semver)
  - Other versions: unaffected
- Vendor: Linux. Product: Linux.
  - affected: `6.13`
  - unaffected: `before 6.13` (semver)
  - unaffected: `6.1.176 to 6.1.*, inclusive` (semver)
  - unaffected: `6.6.143 to 6.6.*, inclusive` (semver)
  - unaffected: `6.12.93 to 6.12.*, inclusive` (semver)
  - unaffected: `6.18.35 to 6.18.*, inclusive` (semver)
  - unaffected: `7.0.12 to 7.0.*, inclusive` (semver)
  - unaffected: `7.1 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

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

- **CISA KEV:** Not listed.
- **EPSS:** 0.0066, the 52nd percentile, on 15 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 19 Jul 2026. New records show when each source confirmed them.

## Sources

- [CVE List: CVE-2026-63968](https://www.cve.org/CVERecord?id=CVE-2026-63968)
- [NVD: CVE-2026-63968](https://nvd.nist.gov/vuln/detail/CVE-2026-63968)

### References from the CNA

- <https://git.kernel.org/stable/c/3948a7d92f7678e89e1776bb2d169afcad63b1ae>
- <https://git.kernel.org/stable/c/c87cd3cb309634bc8f50a54e2079424f219ac21f>
- <https://git.kernel.org/stable/c/0f7b73c3452635de83b8711b31abdda8e49aad7b>
- <https://git.kernel.org/stable/c/ab9a10969a907b472a0196d999c08ff7144172e3>
- <https://git.kernel.org/stable/c/9b9d5bd6e3d4c9cecab5407604b690684b2532d2>
- <https://git.kernel.org/stable/c/9c7da87c2dc860bb17ca1ece942495d28b1ce3b9>

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-2026-63968>
- Everything that needs attention now: <https://agentprime.io/advisories/critical.md>

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The web page: <https://agentprime.io/advisories/CVE-2026-63968/>. Everything for agents: <https://agentprime.io/llms.txt>.