CVE-2026-53271
ksmbd: fix NULL-deref of opinfo->conn in oplock/lease break notifiers
Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix NULL-deref of opinfo->conn in oplock/lease break notifiers smb2_oplock_break_noti() and smb2_lease_break_noti() read opinfo->conn into a local with neither READ_ONCE() nor a NULL check. Both run from oplock_break() after opinfo_get_list() has dropped ci->m_lock, so a concurrent SMB2 LOGOFF (session_fd_check()) can set op->conn = NULL under ci->m_lock within that window. ksmbd_conn_r_count_inc(conn) then writes through NULL at offset 0xc4 -- a remotely triggerable oops. Guard both reads the way compare_guid_key() already does: read opinfo->conn with READ_ONCE() and return early if it is NULL, before allocating the work struct so nothing leaks. A NULL conn means the client is gone and the break is moot, so return 0; oplock_break() treats that as success and runs the normal teardown.
INFO
Published Date :
June 25, 2026, 9:16 a.m.
Last Modified :
July 8, 2026, 4:01 a.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Apply the Linux kernel patch for ksmbd.
- Ensure opinfo->conn is read with READ_ONCE().
- Add a NULL check for opinfo->conn.
- Return early if opinfo->conn is NULL.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-53271.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-53271 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-53271
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
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The following list is the news that have been mention
CVE-2026-53271 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-53271 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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Initial Analysis by [email protected]
Jul. 08, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-476 Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.13 up to (excluding) 6.18.36 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.19 up to (excluding) 7.0.13 *cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.1:rc6:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.9 up to (excluding) 6.12.94 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.6.32 up to (excluding) 6.6.143 Added Reference Type kernel.org: https://git.kernel.org/stable/c/1ff58dcfcab434ebb51649da33774fbb8e1f7b67 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/75e33deda658c1ab3a9336cbdb1436536f9b3660 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/945a86b21b40fb17183f5b27461baa6f03e2467f Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/b003086d76968298f22e7cf62239833b5a3a06b1 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/e735dbd489e3ea02be78dba991056fe1138be51e Types: Patch -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jun. 25, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '8df4bcdb0a4232192b2445256c39b787d58ef14d', 'lessThan': '945a86b21b40fb17183f5b27461baa6f03e2467f', 'versionType': 'git'}, {'status': 'affected', 'version': 'c8efcc786146a951091588e5fa7e3c754850cb3c', 'lessThan': '1ff58dcfcab434ebb51649da33774fbb8e1f7b67', 'versionType': 'git'}, {'status': 'affected', 'version': 'c8efcc786146a951091588e5fa7e3c754850cb3c', 'lessThan': 'e735dbd489e3ea02be78dba991056fe1138be51e', 'versionType': 'git'}, {'status': 'affected', 'version': 'c8efcc786146a951091588e5fa7e3c754850cb3c', 'lessThan': '75e33deda658c1ab3a9336cbdb1436536f9b3660', 'versionType': 'git'}, {'status': 'affected', 'version': 'c8efcc786146a951091588e5fa7e3c754850cb3c', 'lessThan': 'b003086d76968298f22e7cf62239833b5a3a06b1', 'versionType': 'git'}, {'status': 'affected', 'version': '6.6.32', 'lessThan': '6.6.143', 'versionType': 'semver'}], 'programFiles': ['fs/smb/server/oplock.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6.9'}, {'status': 'unaffected', 'version': '0', 'lessThan': '6.9', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.6.143', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.94', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.36', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.0.13', 'versionType': 'semver', 'lessThanOrEqual': '7.0.*'}, {'status': 'unaffected', 'version': '7.1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['fs/smb/server/oplock.c'], 'defaultStatus': 'affected'}] Added Description In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix NULL-deref of opinfo->conn in oplock/lease break notifiers smb2_oplock_break_noti() and smb2_lease_break_noti() read opinfo->conn into a local with neither READ_ONCE() nor a NULL check. Both run from oplock_break() after opinfo_get_list() has dropped ci->m_lock, so a concurrent SMB2 LOGOFF (session_fd_check()) can set op->conn = NULL under ci->m_lock within that window. ksmbd_conn_r_count_inc(conn) then writes through NULL at offset 0xc4 -- a remotely triggerable oops. Guard both reads the way compare_guid_key() already does: read opinfo->conn with READ_ONCE() and return early if it is NULL, before allocating the work struct so nothing leaks. A NULL conn means the client is gone and the break is moot, so return 0; oplock_break() treats that as success and runs the normal teardown. Added Reference https://git.kernel.org/stable/c/1ff58dcfcab434ebb51649da33774fbb8e1f7b67 Added Reference https://git.kernel.org/stable/c/75e33deda658c1ab3a9336cbdb1436536f9b3660 Added Reference https://git.kernel.org/stable/c/945a86b21b40fb17183f5b27461baa6f03e2467f Added Reference https://git.kernel.org/stable/c/b003086d76968298f22e7cf62239833b5a3a06b1 Added Reference https://git.kernel.org/stable/c/e735dbd489e3ea02be78dba991056fe1138be51e