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CVE-2026-89637

Опубликовано: 11 сент. 2026
Источник: redhat
CVSS3: 7.1
EPSS Низкий

Описание

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix UAF and buffer leak in cifs_check_trans2() for malformed secondary T2 When a valid primary TRANSACT2 response has been received (mid->resp_buf set, mid->multiRsp true) and a subsequent secondary response causes cifs_check_trans2() to return false -- either because the SMB header is invalid (malformed != 0) or because check2ndT2() rejects the PDU -- handle_mid() overwrites mid->resp_buf with the new buffer (leaking the primary buffer) and, because mid->multiRsp is set, skips the server->smallbuf/bigbuf NULL-out. When the user thread frees mid->resp_buf, server->smallbuf or server->bigbuf is left dangling; the demux thread reuses it for the next packet, resulting in a use-after-free. Combine both early-exit conditions and, when mid->multiRsp is already set, abort the pending transaction inline: set multiEnd, call dequeue_mid() with malformed=true, and return true so handle_mid() exits without touching mid->resp_buf or the server buffer pointers.

A flaw was found in the Linux kernel's Server Message Block (SMB) client. When processing a malformed secondary TRANSACT2 response, a use-after-free (UAF) vulnerability and a buffer leak can occur in the cifs_check_trans2() function. This can lead to a dangling buffer being reused by the demux thread, potentially allowing an attacker to achieve arbitrary code execution or cause a denial of service.

Затронутые пакеты

ПлатформаПакетСостояниеРекомендацияРелиз
Red Hat OpenShift Container Platform 4openshift/ose-rhel-coreos-8Affected
Red Hat OpenShift Container Platform 4openshift/ose-rhel-coreos-9Affected

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Дополнительная информация

Статус:

Important
Дефект:
CWE-825
https://bugzilla.redhat.com/show_bug.cgi?id=2532405kernel: Kernel: Use-After-Free vulnerability in SMB client due to malformed TRANSACT2 response

EPSS

Процентиль: 46%
0.00588
Низкий

7.1 High

CVSS3

Связанные уязвимости

CVSS3: 9.8
ubuntu
6 дней назад

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix UAF and buffer leak in cifs_check_trans2() for malformed secondary T2 When a valid primary TRANSACT2 response has been received (mid->resp_buf set, mid->multiRsp true) and a subsequent secondary response causes cifs_check_trans2() to return false -- either because the SMB header is invalid (malformed != 0) or because check2ndT2() rejects the PDU -- handle_mid() overwrites mid->resp_buf with the new buffer (leaking the primary buffer) and, because mid->multiRsp is set, skips the server->smallbuf/bigbuf NULL-out. When the user thread frees mid->resp_buf, server->smallbuf or server->bigbuf is left dangling; the demux thread reuses it for the next packet, resulting in a use-after-free. Combine both early-exit conditions and, when mid->multiRsp is already set, abort the pending transaction inline: set multiEnd, call dequeue_mid() with malformed=true, and return true so handle_mid() exits without touchin...

CVSS3: 9.8
nvd
6 дней назад

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix UAF and buffer leak in cifs_check_trans2() for malformed secondary T2 When a valid primary TRANSACT2 response has been received (mid->resp_buf set, mid->multiRsp true) and a subsequent secondary response causes cifs_check_trans2() to return false -- either because the SMB header is invalid (malformed != 0) or because check2ndT2() rejects the PDU -- handle_mid() overwrites mid->resp_buf with the new buffer (leaking the primary buffer) and, because mid->multiRsp is set, skips the server->smallbuf/bigbuf NULL-out. When the user thread frees mid->resp_buf, server->smallbuf or server->bigbuf is left dangling; the demux thread reuses it for the next packet, resulting in a use-after-free. Combine both early-exit conditions and, when mid->multiRsp is already set, abort the pending transaction inline: set multiEnd, call dequeue_mid() with malformed=true, and return true so handle_mid() exits without touchin

CVSS3: 9.8
debian
6 дней назад

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

CVSS3: 9.8
github
6 дней назад

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix UAF and buffer leak in cifs_check_trans2() for malformed secondary T2 When a valid primary TRANSACT2 response has been received (mid->resp_buf set, mid->multiRsp true) and a subsequent secondary response causes cifs_check_trans2() to return false -- either because the SMB header is invalid (malformed != 0) or because check2ndT2() rejects the PDU -- handle_mid() overwrites mid->resp_buf with the new buffer (leaking the primary buffer) and, because mid->multiRsp is set, skips the server->smallbuf/bigbuf NULL-out. When the user thread frees mid->resp_buf, server->smallbuf or server->bigbuf is left dangling; the demux thread reuses it for the next packet, resulting in a use-after-free. Combine both early-exit conditions and, when mid->multiRsp is already set, abort the pending transaction inline: set multiEnd, call dequeue_mid() with malformed=true, and return true so handle_mid() exits without touc...

EPSS

Процентиль: 46%
0.00588
Низкий

7.1 High

CVSS3