5.5
MEDIUM CVSS 3.1
CVE-2026-52996
ksmbd: fix durable fd leak on ClientGUID mismatch in durable v2 open
Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix durable fd leak on ClientGUID mismatch in durable v2 open ksmbd_lookup_fd_cguid() returns a ksmbd_file with its refcount incremented via ksmbd_fp_get(). parse_durable_handle_context() in the DURABLE_REQ_V2 case properly releases this reference on every path inside the ClientGUID-match branch, either by calling ksmbd_put_durable_fd() or by transferring ownership to dh_info->fp for a successful reconnect. However, when an entry exists in the global file table with the same CreateGuid but a different ClientGUID, the code simply falls through to the new-open path without dropping the reference obtained from ksmbd_lookup_fd_cguid(). Per MS-SMB2 section 3.3.5.9.10 ("Handling the SMB2_CREATE_DURABLE_HANDLE_REQUEST_V2 Create Context"), the server MUST locate an Open whose Open.CreateGuid matches the request's CreateGuid AND whose Open.ClientGuid matches the ClientGuid of the connection that received the request. If no such Open is found, the server MUST continue with the normal open execution phase. A CreateGuid hit with a ClientGUID mismatch is therefore the "Open not found" case: proceeding with a new open is correct, but the reference obtained purely as a side effect of the lookup must not be leaked. Repeated requests that hit this mismatch pin global_ft entries, prevent __ksmbd_close_fd() from ever running for the corresponding files, and defeat the durable scavenger, leading to long-lived resource leaks. Release the reference in the mismatch path and clear dh_info->fp so subsequent logic does not mistake a non-matching lookup result for a reconnect target.

INFO

Published Date :

June 24, 2026, 5:17 p.m.

Last Modified :

July 15, 2026, 1:04 p.m.

Remotely Exploit :

No

Source :

416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products

The following products are affected by CVE-2026-52996 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Linux linux_kernel
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 3.1 MEDIUM [email protected]
Solution
Fix a file descriptor leak in ksmbd caused by mismatched ClientGUIDs during durable handle v2 opens.
  • Update the Linux kernel to include the ksmbd fix.
  • Ensure the fix addresses the durable fd leak.
  • Verify ClientGUID matching logic in ksmbd.
  • Monitor for resource leaks after applying the update.
References to Advisories, Solutions, and Tools
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-52996 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-2026-52996 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).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-52996 vulnerability anywhere in the article.

The following table lists the changes that have been made to the CVE-2026-52996 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.

  • Initial Analysis by [email protected]

    Jul. 15, 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-401
    Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.13 up to (excluding) 6.18.33 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.19 up to (excluding) 7.0.10 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.6.32 up to (excluding) 6.6.141 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.9 up to (excluding) 6.12.91
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/06f709d0e531f3e54d88665dd426be3998a774e6 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/407b6e699ba8b45b72cc265eed8a1bc8a7191609 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/804054d19886ac6628883d82410f6ee42a818664 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/8c4a0ef19c8264c150833131af34541495832cd0 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/f31beef633fbf2b5af7805fa187a10bcff1d4b49 Types: Patch
  • New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Jun. 24, 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': '407b6e699ba8b45b72cc265eed8a1bc8a7191609', 'versionType': 'git'}, {'status': 'affected', 'version': 'c8efcc786146a951091588e5fa7e3c754850cb3c', 'lessThan': 'f31beef633fbf2b5af7805fa187a10bcff1d4b49', 'versionType': 'git'}, {'status': 'affected', 'version': 'c8efcc786146a951091588e5fa7e3c754850cb3c', 'lessThan': '06f709d0e531f3e54d88665dd426be3998a774e6', 'versionType': 'git'}, {'status': 'affected', 'version': 'c8efcc786146a951091588e5fa7e3c754850cb3c', 'lessThan': '8c4a0ef19c8264c150833131af34541495832cd0', 'versionType': 'git'}, {'status': 'affected', 'version': 'c8efcc786146a951091588e5fa7e3c754850cb3c', 'lessThan': '804054d19886ac6628883d82410f6ee42a818664', 'versionType': 'git'}, {'status': 'affected', 'version': '6.6.32', 'lessThan': '6.6.141', 'versionType': 'semver'}], 'programFiles': ['fs/smb/server/smb2pdu.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': '6.6.141', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.91', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.33', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.0.10', 'versionType': 'semver', 'lessThanOrEqual': '7.0.*'}, {'status': 'unaffected', 'version': '7.1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['fs/smb/server/smb2pdu.c'], 'defaultStatus': 'affected'}]
    Added Description In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix durable fd leak on ClientGUID mismatch in durable v2 open ksmbd_lookup_fd_cguid() returns a ksmbd_file with its refcount incremented via ksmbd_fp_get(). parse_durable_handle_context() in the DURABLE_REQ_V2 case properly releases this reference on every path inside the ClientGUID-match branch, either by calling ksmbd_put_durable_fd() or by transferring ownership to dh_info->fp for a successful reconnect. However, when an entry exists in the global file table with the same CreateGuid but a different ClientGUID, the code simply falls through to the new-open path without dropping the reference obtained from ksmbd_lookup_fd_cguid(). Per MS-SMB2 section 3.3.5.9.10 ("Handling the SMB2_CREATE_DURABLE_HANDLE_REQUEST_V2 Create Context"), the server MUST locate an Open whose Open.CreateGuid matches the request's CreateGuid AND whose Open.ClientGuid matches the ClientGuid of the connection that received the request. If no such Open is found, the server MUST continue with the normal open execution phase. A CreateGuid hit with a ClientGUID mismatch is therefore the "Open not found" case: proceeding with a new open is correct, but the reference obtained purely as a side effect of the lookup must not be leaked. Repeated requests that hit this mismatch pin global_ft entries, prevent __ksmbd_close_fd() from ever running for the corresponding files, and defeat the durable scavenger, leading to long-lived resource leaks. Release the reference in the mismatch path and clear dh_info->fp so subsequent logic does not mistake a non-matching lookup result for a reconnect target.
    Added Reference https://git.kernel.org/stable/c/06f709d0e531f3e54d88665dd426be3998a774e6
    Added Reference https://git.kernel.org/stable/c/407b6e699ba8b45b72cc265eed8a1bc8a7191609
    Added Reference https://git.kernel.org/stable/c/804054d19886ac6628883d82410f6ee42a818664
    Added Reference https://git.kernel.org/stable/c/8c4a0ef19c8264c150833131af34541495832cd0
    Added Reference https://git.kernel.org/stable/c/f31beef633fbf2b5af7805fa187a10bcff1d4b49
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.