Security readout for executives and security teams
Plain-English summary
A flaw in the Linux SMB client can make the kernel read memory after it has been freed when directory listings occur concurrently. Successful triggering could crash the system or potentially compromise kernel confidentiality and integrity. Exposure requires an affected kernel using CIFS/SMB functionality and local access.
Executive priority
Treat as a high-priority kernel maintenance issue on SMB-using Linux systems, especially multi-user or shared-compute hosts. Patch through supported distribution channels after normal compatibility testing. Systems without CIFS usage have materially lower practical exposure, but should still receive routine kernel updates.
Technical view
CVE-2025-38051 is a race-related use-after-free in cifs_fill_dirent during concurrent readdir operations. One process can release a CIFS response buffer while another still accesses it. KASAN confirmed a four-byte read from freed slab memory. CVSS 3.1 rates it 7.8: local, low-complexity, low-privilege, no user interaction.
Likely exposure
Likely exposure is limited to Linux hosts running affected, unpatched kernels where the CIFS client is present and SMB directory enumeration can occur concurrently. File servers, workstations, containers sharing the host kernel, and appliances mounting SMB shares merit review. Distribution backports make version-only conclusions unreliable.
Exploitation context
The source reports that a proof of concept is available, demonstrating triggerability. The CVE is not listed as KEV, and the supplied sources provide no evidence of active exploitation. The attack vector is local and requires low privileges; remote-only exposure is not established.
Researcher notes
The evidence establishes a concurrency race and slab use-after-free in the CIFS readdir path. The supplied trace shows allocation in cifs_demultiplex_thread, release in cifs_readdir, and later access in cifs_fill_dirent. The bundle is truncated and does not establish reliable exploitation beyond triggering the memory-safety violation.
Mitigation direction
- Install a vendor-supported kernel containing the applicable upstream stable fix.
- Follow distribution advisories because vendors may backport fixes without changing to an upstream version.
- Prioritize hosts mounting SMB shares or exposing CIFS operations to untrusted local users.
- If patching is delayed, restrict untrusted local access and unnecessary SMB client usage.
Validation and detection
- Inventory kernel versions and identify hosts loading CIFS or mounting SMB shares.
- Map each kernel package to its vendor advisory or backported fix status.
- Confirm the installed kernel includes the relevant stable commit for its branch.
- Review kernel logs for CIFS faults, use-after-free reports, KASAN alerts, or unexplained crashes.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
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CVE-2025-38051 mapping review
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Open ATT&CK lookup- Severity
- High
- CVSS
- 7.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9LinuxVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://git.kernel.org/stable/c/aee067e88d61eb72e966f094e4749c6b14e7008fCVE reference, Linux
- https://git.kernel.org/stable/c/a24c2f05ac3c5b0aaa539d9d913826d2643dfd0eCVE reference, Linux
- https://git.kernel.org/stable/c/1b197931fbc821bc7e9e91bf619400db563e3338CVE reference, Linux
- https://git.kernel.org/stable/c/c8623231e0edfcccb7cc6add0288fa0f0594282fCVE reference, Linux
- https://git.kernel.org/stable/c/73cadde98f67f76c5eba00ac0b72c453383cec8bCVE reference, Linux
- https://git.kernel.org/stable/c/9bea368648ac46f8593a780760362e40291d22a9CVE reference, Linux
- https://git.kernel.org/stable/c/9c9aafbacc183598f064902365e107b5e856531fCVE reference, Linux
- https://git.kernel.org/stable/c/a7a8fe56e932a36f43e031b398aef92341bf5ea0CVE reference, Linux
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.htmlCVE reference, CVE
- https://lists.debian.org/debian-lts-announce/2025/10/msg00007.htmlCVE reference, CVE
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.