CVE-2021-39636

kernel: information disclosure due to uninitialized data in do_ipt_get_ctl() and do_ipt_set_ctl() in ip_tables.c

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Severity

Moderate

Red Hat Product Security

4.4

CVSS 3.1

Review impact separately from score.

Published · December 6, 2021

Updated · November 22, 2025

Description

A vulnerability was found in the Linux kernel’s net/ipv6/netfilter/ip6_tables.c:copy_entries_to_user function. This flaw allows a local attacker to leak internal kernel information.

CVSS score applicability

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation

To mitigate this issue, prevent the module ip6_tables from being loaded.

Please see https://access.redhat.com/solutions/41278

for information on how to blacklist a kernel module to prevent it from loading automatically.

CVSS / CWE

CVSS 3.1 · 4.4
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N

CWE-200 · Exposure of Sensitive Information to an Unauthorized Actor