Vulnerability in Linux kernel (CVE-2026-52996)
Summary
Vulnerability in Linux kernel (CVE-2026-52996). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
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…
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-52996 has been found in Linux kernel.
Risk of unauthorized operations or information disclosure. CVSS score: 5.5/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-52996" on the vendor's site.
CVE-2026-52996 (Linux kernel) — CWE-401 / CVSS v3 5.5
Attack vector: local / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-401) exists in Linux kernel.
Check the vendor advisory for the affected versions of Linux kernel.
Severity: Medium (CVSS 5.5/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Linux kernel を使っているサービスとバージョンを洗い出す。
-
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2026-52996 linux-lts Fixed in: 6.12.92-r0
- Debian DEBIAN-CVE-2026-52996 linux Fixed in: 6.12.94-1
- Ubuntu UBUNTU-CVE-2026-52996 linux-hwe-edge
References
- advisory nvd.nist.gov
- advisory github.com
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web github.com