CVE-2026-53271: Linux kernel · NULL Pointer Dereference
Source GCVE Database
Not known to be exploited · CVSS 5.5 Medium.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 25 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
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.
References
- nvd.nist.gov/vuln/detail/CVE-2026-53271 (opens in a new tab)
- git.kernel.org/stable/c/1ff58dcfcab434ebb51649da33774fbb8e1f7b67 (opens in a new tab)
- git.kernel.org/stable/c/75e33deda658c1ab3a9336cbdb1436536f9b3660 (opens in a new tab)
- git.kernel.org/stable/c/945a86b21b40fb17183f5b27461baa6f03e2467f (opens in a new tab)
- git.kernel.org/stable/c/b003086d76968298f22e7cf62239833b5a3a06b1 (opens in a new tab)
- git.kernel.org/stable/c/e735dbd489e3ea02be78dba991056fe1138be51e (opens in a new tab)