What is CVE-2026-99042?

CVE-2026-99042 is a High severity Linux kernel vulnerability with a CVSS score of 8.4 out of 10, affecting Linux kernel versions from 7.2 onward and patched in 7.2.11 and 7.3. CVE-2026-99042 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2026-99042?

CVE-2026-99042 has a CVSS score of 8.4 out of 10, rated High severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N.

Is there a patch available for CVE-2026-99042?

Yes, CVE-2026-99042 has been patched. Fixed versions include 7.2.11 and 7.3. If you are running Linux kernel 7.2 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2026-99042 actively exploited?

CVE-2026-99042 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2026-99042

High

In the Linux kernel, the following vulnerability has been resolved: io_uring/net: populate CONNECT filter fields for 24-byte sockaddr_in6 io_connect_bpf_populate() fills connect.port and connect.v6_addr for AF_INET6 only when addr_len >= sizeof(struct sockaddr_in6), i.e. 28 bytes. The IPv6 connect paths accept SIN6_LEN_RFC2133 (24 bytes), which already holds sin6_port and sin6_addr. io_connect() passes addr_len to the socket layer unchanged. At addr_len 24 the filter sees family AF_INET6 with port and address zero, while the kernel connects to the real destination. A filter that denies an IPv6 port or address is bypassed. Denying connect.port == P rejects [::1]:P with -EACCES at addr_len 28 but connects at addr_len 24. Use SIN6_LEN_RFC2133 as the threshold. sin6_scope_id stays zero when absent. The threshold mismatch was found by an AI coding assistant (Claude Code) comparing this hook against the net/ipv6 length checks on my instructions; it also drafted the reproducer and this patch. I verified the bypass and the fix in a VM on 7.3-rc6 and that 7.2 has the same code.

Package Linux Kernel

Published 2026-10-23

Last modified 2026-10-24

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

8.4

out of 10

High

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

None

Vector string

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

Affected versions

Linux kernel versions 7.2 and later are affected. Fixed in 7.2.11, 7.3 and their respective stable series.

Affected from

≥ 7.2

Fixed in

✓ 7.2.11 7.2.x ✓ 7.3

References

2 total

Details

CVE ID CVE-2026-99042

Severity High

CVSS score 8.4 / 10

CVSS version 3.1

Published 2026-10-23

Modified 2026-10-24

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2026-99042?

CVE-2026-99042 is a High severity Linux kernel vulnerability with a CVSS score of 8.4 out of 10 . It affects Linux kernel versions from 7.2 onward and has been patched in 7.2.11 and 7.3. CVE-2026-99042 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2026-99042?

CVE-2026-99042 has a CVSS score of 8.4 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N.
Is there a patch available for CVE-2026-99042?

Yes. CVE-2026-99042 has been patched. Fixed versions include 7.2.11 and 7.3. If you are running Linux kernel 7.2 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2026-99042 actively exploited?

No. CVE-2026-99042 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.