Security readout for executives and security teams
Plain-English summary
A flaw in Linux Shared Memory Communications can crash the kernel when software RoCE is used and an expected device pointer is missing. The stated impact is service disruption, not data theft or modification. Systems using the affected networking configuration deserve prompt review; ordinary Linux systems without SMC and software RoCE appear less likely to encounter the vulnerable path.
Executive priority
Prioritize remediation on production, externally reachable, or high-availability systems using SMC with software RoCE. Handle other Linux systems through normal high-severity patching after confirming configuration and vendor status. Escalate immediately if relevant kernel crashes are observed, but do not represent the issue as actively exploited based on current evidence.
Technical view
The SMC kernel module can dereference a NULL ibdev->dma_device pointer in smc_ib_is_sg_need_sync() while mapping buffers for a software RoCE device. This produces a kernel oops and potentially a denial of service. The published correction adds NULL-pointer detection. CVSS 3.1 is 7.5: network-accessible, low complexity, no privileges or interaction, with availability impact only.
Likely exposure
Exposure is concentrated in affected Linux kernels where SMC is enabled and uses a software RoCE device. The supplied record identifies affected releases including 6.0, 6.1.151, 6.6.105, 6.12.46, 6.16.6, and 6.17. Distribution backports may change actual status, so version numbers alone are insufficient.
Exploitation context
The CVSS vector characterizes this as remotely reachable, but the supplied description does not document the exact network conditions required to trigger the crash. It provides no evidence of public exploitation, and the CVE is not listed as KEV. Treat it as a credible denial-of-service risk without claiming active exploitation.
Researcher notes
The observed fault occurs in an SMC handshake workqueue through smcr_buf_map_link() and buffer creation. The prerequisite documented by the source is a software RoCE device whose ibdev->dma_device is NULL. Multiple stable-kernel commits are referenced, suggesting branch-specific backports. The supplied material does not establish exploit reliability, affected distribution builds, or whether every listed release remains vulnerable after backporting.
Mitigation direction
- Install a vendor-supported kernel containing the applicable upstream fix or distribution backport.
- Prioritize systems using Linux SMC with software RoCE networking.
- If patching is delayed, consult vendor guidance for supported ways to avoid the affected configuration.
- Review Debian, Siemens, or other relevant vendor advisories for product-specific remediation status.
Validation and detection
- Inventory kernel versions and determine whether SMC and software RoCE are enabled.
- Confirm the installed kernel contains the applicable fix or vendor backport.
- Check kernel logs for SMC-related NULL dereferences, oops events, or unexpected reboots.
- Validate remediation in a controlled environment using normal SMC connection testing.
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-2025-39857 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
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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:N/I:N/A:H3.93.6LinuxVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://git.kernel.org/stable/c/0cdf1fd8fc59d44a48c694324611136910301ef9CVE reference, Linux
- https://git.kernel.org/stable/c/f18d9b3abf9c6587372cc702f963a7592277ed56CVE reference, Linux
- https://git.kernel.org/stable/c/eb929910bd4b4165920fa06a87b22cc6cae92e0eCVE reference, Linux
- https://git.kernel.org/stable/c/34f17cbe027050b8d5316ea1b6f9bd7c378e92deCVE reference, Linux
- https://git.kernel.org/stable/c/ba1e9421cf1a8369d25c3832439702a015d6b5f9CVE reference, Linux
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.htmlCVE reference, CVE
- https://cert-portal.siemens.com/productcert/html/ssa-032379.htmlCVE reference, siemens-SADP
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.