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CVE-2026-43026

Опубликовано: 01 мая 2026
Источник: redhat
CVSS3: 6.1

Описание

In the Linux kernel, the following vulnerability has been resolved: netfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent ctnetlink_alloc_expect() allocates expectations from a non-zeroing slab cache via nf_ct_expect_alloc(). When CTA_EXPECT_NAT is not present in the netlink message, saved_addr and saved_proto are never initialized. Stale data from a previous slab occupant can then be dumped to userspace by ctnetlink_exp_dump_expect(), which checks these fields to decide whether to emit CTA_EXPECT_NAT. The safe sibling nf_ct_expect_init(), used by the packet path, explicitly zeroes these fields. Zero saved_addr, saved_proto and dir in the else branch, guarded by IS_ENABLED(CONFIG_NF_NAT) since these fields only exist when NAT is enabled. Confirmed by priming the expect slab with NAT-bearing expectations, freeing them, creating a new expectation without CTA_EXPECT_NAT, and observing that the ctnetlink dump emits a spurious CTA_EXPECT_NAT containing stale data from the prior allocation.

A flaw was found in the Linux kernel's netfilter component, specifically within the ctnetlink module. This vulnerability occurs because certain fields are not properly initialized when a new connection tracking expectation is created without the Network Address Translation (NAT) expectation attribute. This oversight can lead to the disclosure of stale data from previously used memory, which a local user could potentially access. This information disclosure could expose sensitive data from the kernel to an unprivileged user.

Отчет

This Moderate-severity flaw in the Linux kernel's netfilter component allows a local attacker to disclose stale kernel memory. Uninitialized fields within connection tracking expectations, when the Network Address Translation (NAT) attribute is not present, can expose sensitive data to an unprivileged local user.

Меры по смягчению последствий

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

Затронутые пакеты

ПлатформаПакетСостояниеРекомендацияРелиз
Red Hat Enterprise Linux 10kernelFix deferred
Red Hat Enterprise Linux 6kernelOut of support scope
Red Hat Enterprise Linux 7kernelFix deferred
Red Hat Enterprise Linux 7kernel-rtFix deferred
Red Hat Enterprise Linux 8kernelFix deferred
Red Hat Enterprise Linux 8kernel-rtFix deferred
Red Hat Enterprise Linux 9kernelFix deferred
Red Hat Enterprise Linux 9kernel-rtFix deferred

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Дополнительная информация

Статус:

Moderate
Дефект:
CWE-824
https://bugzilla.redhat.com/show_bug.cgi?id=2464403kernel: netfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent

6.1 Medium

CVSS3

Связанные уязвимости

CVSS3: 5.5
ubuntu
3 месяца назад

In the Linux kernel, the following vulnerability has been resolved: netfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent ctnetlink_alloc_expect() allocates expectations from a non-zeroing slab cache via nf_ct_expect_alloc(). When CTA_EXPECT_NAT is not present in the netlink message, saved_addr and saved_proto are never initialized. Stale data from a previous slab occupant can then be dumped to userspace by ctnetlink_exp_dump_expect(), which checks these fields to decide whether to emit CTA_EXPECT_NAT. The safe sibling nf_ct_expect_init(), used by the packet path, explicitly zeroes these fields. Zero saved_addr, saved_proto and dir in the else branch, guarded by IS_ENABLED(CONFIG_NF_NAT) since these fields only exist when NAT is enabled. Confirmed by priming the expect slab with NAT-bearing expectations, freeing them, creating a new expectation without CTA_EXPECT_NAT, and observing that the ctnetlink dump emits a spurious CTA_EXPECT_NAT containing stale data from...

CVSS3: 5.5
nvd
3 месяца назад

In the Linux kernel, the following vulnerability has been resolved: netfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent ctnetlink_alloc_expect() allocates expectations from a non-zeroing slab cache via nf_ct_expect_alloc(). When CTA_EXPECT_NAT is not present in the netlink message, saved_addr and saved_proto are never initialized. Stale data from a previous slab occupant can then be dumped to userspace by ctnetlink_exp_dump_expect(), which checks these fields to decide whether to emit CTA_EXPECT_NAT. The safe sibling nf_ct_expect_init(), used by the packet path, explicitly zeroes these fields. Zero saved_addr, saved_proto and dir in the else branch, guarded by IS_ENABLED(CONFIG_NF_NAT) since these fields only exist when NAT is enabled. Confirmed by priming the expect slab with NAT-bearing expectations, freeing them, creating a new expectation without CTA_EXPECT_NAT, and observing that the ctnetlink dump emits a spurious CTA_EXPECT_NAT containing stale data fr

CVSS3: 5.5
debian
3 месяца назад

In the Linux kernel, the following vulnerability has been resolved: n ...

CVSS3: 5.5
github
3 месяца назад

In the Linux kernel, the following vulnerability has been resolved: netfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent ctnetlink_alloc_expect() allocates expectations from a non-zeroing slab cache via nf_ct_expect_alloc(). When CTA_EXPECT_NAT is not present in the netlink message, saved_addr and saved_proto are never initialized. Stale data from a previous slab occupant can then be dumped to userspace by ctnetlink_exp_dump_expect(), which checks these fields to decide whether to emit CTA_EXPECT_NAT. The safe sibling nf_ct_expect_init(), used by the packet path, explicitly zeroes these fields. Zero saved_addr, saved_proto and dir in the else branch, guarded by IS_ENABLED(CONFIG_NF_NAT) since these fields only exist when NAT is enabled. Confirmed by priming the expect slab with NAT-bearing expectations, freeing them, creating a new expectation without CTA_EXPECT_NAT, and observing that the ctnetlink dump emits a spurious CTA_EXPECT_NAT containing stale data...

CVSS3: 5.5
fstec
4 месяца назад

Уязвимость функции ctnetlink_alloc_expect() ядра операционных систем Linux, позволяющая нарушителю раскрыть конфиденциальную информацию

6.1 Medium

CVSS3

Уязвимость CVE-2026-43026