What is CVE-2026-99999?

CVE-2026-99999 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.3 out of 10, affecting Linux kernel versions from 2.6.27 onward and patched in 5.10.272, 5.15.223, 6.1.190 and others. CVE-2026-99999 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-99999?

CVE-2026-99999 has a CVSS score of 9.3 out of 10, rated Critical severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.

Is there a patch available for CVE-2026-99999?

Yes, CVE-2026-99999 has been patched. Fixed versions include 5.10.272, 5.15.223, 6.1.190 and others. If you are running Linux kernel 2.6.27 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-99999 actively exploited?

CVE-2026-99999 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-99999

Critical

In the Linux kernel, the following vulnerability has been resolved: ipv4: validate checksum_start before completing checksum If a packet with bad checksum metadata gets into the ipv4 stack, skb_checksum_help can corrupt the network header and cause a bunch of mischief. This was discovered and reported by Paulos, and has been reporoduced by others independently since. We really shouldn't allow such packets in, but as a defence in depth measure, let's also check before we complete the checksum. A more complete validation at input is forthcoming, but needs more work.

Package Linux Kernel

Published 2026-10-15

Last modified 2026-10-15

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

9.3

out of 10

Critical

Attack Vector

Local

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Vector string

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Affected versions

Linux kernel versions 2.6.27 and later are affected. Fixed in 5.10.272, 5.15.223, 6.1.190, 6.6.159, 6.12.113, 6.18.57, 7.2.11, 7.3-rc7 and their respective stable series.

Affected from

≥ 2.6.27

Fixed in

✓ 5.10.272 5.10.x ✓ 5.15.223 5.15.x ✓ 6.1.190 6.1.x ✓ 6.6.159 6.6.x ✓ 6.12.113 6.12.x ✓ 6.18.57 6.18.x ✓ 7.2.11 7.2.x ✓ 7.3-rc7

References

11 total

Showing 5 of 11 references View all on NVD

Details

CVE ID CVE-2026-99999

Severity Critical

CVSS score 9.3 / 10

CVSS version 3.1

Published 2026-10-15

Modified 2026-10-15

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-99999?

CVE-2026-99999 is a Critical severity Linux kernel vulnerability with a CVSS score of 9.3 out of 10 . It affects Linux kernel versions from 2.6.27 onward and has been patched in 5.10.272, 5.15.223, 6.1.190 and others. CVE-2026-99999 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-99999?

CVE-2026-99999 has a CVSS score of 9.3 out of 10, rated Critical severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.
Is there a patch available for CVE-2026-99999?

Yes. CVE-2026-99999 has been patched. Fixed versions include 5.10.272, 5.15.223, 6.1.190 and others. If you are running Linux kernel 2.6.27 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-99999 actively exploited?

No. CVE-2026-99999 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.