Security readout for executives and security teams
Plain-English summary
This Linux kernel issue can crash a system when a race condition frees an SMC socket while another kernel path still uses it. The business impact is availability, not data theft. Exploitation requires local access, low privileges, and high complexity, so prioritize exposed multi-user Linux systems over isolated hosts.
Executive priority
Treat this as a scheduled availability-risk patch, not an emergency breach response. Give higher priority to shared Linux servers, container hosts, and environments with untrusted local users. No active exploitation is cited in the provided sources.
Technical view
CVE-2021-46925 is a CWE-362 race in Linux SMC handling. smc_cdc_tx_handler() can touch smc_sock after smc_release() has freed it, causing a kernel page fault and panic. The fix adds refcounting for inflight CDC messages and changes QP teardown behavior so pending completion handling cannot reference freed state.
Likely exposure
Exposure is limited to Linux kernels in the affected set, particularly systems using or enabling SMC networking. The CVSS vector is local, high-complexity, low-privilege, no user interaction, with high availability impact. Distribution backports may change practical exposure, so version checks alone may be insufficient.
Exploitation context
The source bundle does not show KEV listing or active exploitation. The issue is locally reachable and complex, with impact described as kernel panic. There is no source evidence of remote exploitation, public weaponization, data exposure, or privilege escalation.
Researcher notes
The bug centers on lifetime management between smc_cdc_tx_handler() and smc_release(). The fix uses smc_connection refcounts for inflight CDC messages and waits for pending WQEs/CQEs. Validate backports by code or changelog, because distribution kernel versions may not align with upstream stable versions.
Mitigation direction
- Apply Linux kernel updates that include the referenced stable fixes.
- Use distribution vendor kernels with confirmed backported fixes.
- Check vendor guidance where upstream version mapping is unclear.
- Prioritize multi-user Linux systems and hosts with SMC in use.
Validation and detection
- Inventory running Linux kernel versions across affected systems.
- Confirm whether the referenced stable commits are present or backported.
- Check whether SMC support is enabled or operationally required.
- Review crash logs for kernel panics in smc_cdc_tx_handler paths.
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.
CWE-362: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-46925 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
- Medium
- CVSS
- 4.7 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:H/PR:L/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.
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:H/PR:L/UI:N/S:U/C:N/I:N/A:H13.6CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
4.7MediumVector: CVSS:3.1/AV:L/AC:H/PR:L/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/e8a5988a85c719ce7205cb00dcf0716dcf611332CVE reference, Linux
- https://git.kernel.org/stable/c/b85f751d71ae8e2a15e9bda98852ea9af35282ebCVE reference, Linux
- https://git.kernel.org/stable/c/349d43127dac00c15231e8ffbcaabd70f7b0e544CVE 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.
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.