Security readout for executives and security teams
Plain-English summary
A flaw in Linux’s ksmbd SMB server allowed certain network requests to bypass expected size checks. On an exposed affected system, a remote unauthenticated attacker could potentially disclose sensitive data or disrupt service. The supplied CVSS score is 9.1, reflecting serious confidentiality and availability consequences.
Executive priority
Prioritize remediation for externally reachable or broadly accessible ksmbd servers because exploitation conditions require no authentication or user action. Validate internal-only systems promptly, but rank them by network reachability and data sensitivity. The supplied evidence supports critical technical severity, not confirmed active exploitation.
Technical view
ksmbd validated command payload size incompletely: except for SMB2_OPLOCK_BREAK_HE, other command request sizes were not checked as expected. The Linux fix adds request-size validation for those commands. The supplied CVSS v3.1 vector indicates network access, low complexity, no privileges, no user interaction, high confidentiality impact, and high availability impact.
Likely exposure
Exposure requires an affected Linux kernel using ksmbd, with its SMB service reachable by an attacker. The supplied affected-version data names 6.4, 5.15.127, 6.1.46, 6.4.11, and 6.5, but its version entries are ambiguous; confirm status through the applicable Linux distributor.
Exploitation context
The CVSS vector describes remote, unauthenticated, low-complexity attack conditions. However, this CVE is not listed as KEV in the supplied bundle, and the provided sources do not establish active exploitation. Treat internet-reachable ksmbd services as higher priority without claiming exploitation is occurring.
Researcher notes
The core defect and fix direction are clear, but affected-version interpretation is not. The bundle mixes commit identifiers, release numbers, an unexplained “0,” and seemingly non-monotonic affected and unaffected releases. Avoid deriving vulnerable ranges from these entries alone; use distributor backport information and inspect whether the stable fix is present.
Mitigation direction
- Identify systems running ksmbd and prioritize those exposing SMB to untrusted networks.
- Apply a vendor-supported kernel containing the linked request-size validation fix.
- Consult the relevant Linux distributor because the supplied version-status records are ambiguous.
- Restrict SMB network access until affected systems are confirmed fixed.
Validation and detection
- Record each system’s kernel version and Linux distributor.
- Confirm whether ksmbd is enabled, loaded, or providing SMB service.
- Determine whether SMB is reachable from internet or other untrusted networks.
- Compare the installed kernel against distributor guidance and the linked stable fixes.
- After updating, verify the running kernel is the intended vendor-fixed build.
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
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2023-4515 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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.
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:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H3.95.2LinuxVulnerability scoring details
Base CVSS 3.1 score
9.1CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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.
Source materials
- CVE List V5 sourceCVE List V5
- https://git.kernel.org/stable/c/595679098bdcdbfbba91ebe07a2f7f208df93870CVE reference, Linux
- https://git.kernel.org/stable/c/c6bef3bc30fd4a175aef846b7d928a6c40d091cdCVE reference, Linux
- https://git.kernel.org/stable/c/ff7236b66d69582f90cf5616e63cfc3dc18142bbCVE reference, Linux
- https://git.kernel.org/stable/c/5aa4fda5aa9c2a5a7bac67b4a12b089ab81fee3cCVE reference, Linux
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.