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CVE Record

CVE-2025-71182: can: j1939: make j1939_session_activate() fail if device is no longer registered

In the Linux kernel, the following vulnerability has been resolved: can: j1939: make j1939_session_activate() fail if device is no longer registered syzbot is still reporting unregister_netdevice: waiting for vcan0 to become free. Usage count = 2 even after commit 93a27b5891b8 ("can: j1939: add missing calls in NETDEV_UNREGISTER notification handler") was added. A debug printk() patch found that j1939_session_activate() can succeed even after j1939_cancel_active_session() from j1939_netdev_notify(NETDEV_UNREGISTER) has completed. Since j1939_cancel_active_session() is processed with the session list lock held, checking ndev->reg_state in j1939_session_activate() with the session list lock held can reliably close the race window.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2025-71182 is a Linux kernel flaw in the CAN J1939 networking code. A race during network device unregister can leave a virtual CAN device held in use, producing a kernel wait condition. The public record does not provide CVSS, CWE, or confirmed exploitation evidence.

Executive priority

Treat this as a targeted kernel maintenance issue, not an internet-scale emergency based on current evidence. Prioritize affected operational technology, automotive, and embedded Linux fleets where CAN/J1939 is used.

Technical view

The issue is in j1939_session_activate(). It could succeed after NETDEV_UNREGISTER handling had cancelled active sessions. The fix adds a protected check of the network device registration state while holding the session list lock, closing the race window during device teardown.

Likely exposure

Exposure appears limited to Linux systems with CAN J1939 functionality present and relevant kernel versions. This is most relevant to embedded, automotive, industrial, test, or systems using SocketCAN/vcan. Distribution backports may change exact exposure.

Exploitation context

The bundle cites syzbot reports and Linux stable fixes, not active exploitation. CISA KEV status is false. No public exploitability details, attacker prerequisites, or weaponized exploit evidence are provided in the source bundle.

Researcher notes

Evidence supports a race-condition fix in Linux CAN J1939 teardown handling. The source bundle does not include CVSS, CWE, exploit status, or impact classification beyond the unregister_netdevice usage-count symptom and stable patch references.

Mitigation direction

  • Apply vendor kernel updates that include the referenced Linux stable fixes.
  • Check distribution advisories for backported fixes matching your deployed kernel package.
  • Prioritize hosts using CAN, J1939, vcan, or automotive networking workloads.
  • If CAN J1939 is unnecessary, review vendor-supported ways to reduce that exposure.

Validation and detection

  • Inventory kernel versions and compare them with vendor fixed package guidance.
  • Confirm whether CAN J1939 modules or functionality are enabled on affected systems.
  • Review kernel logs for unregister_netdevice waits involving CAN or vcan devices.
  • Verify patched kernels include the referenced j1939_session_activate() registration-state check.
Prepared
Confidence
medium
Sources
9

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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-2025-71182 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

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.

0CVSS vectors
3Timeline events
0ADP providers
8Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux9d71dd0c70099914fcd063135da3c580865e924c, 9d71dd0c70099914fcd063135da3c580865e924c, 9d71dd0c70099914fcd063135da3c580865e924c, 9d71dd0c70099914fcd063135da3c580865e924c, 9d71dd0c70099914fcd063135da3c580865e924c, 9d71dd0c70099914fcd063135da3c580865e924c, 9d71dd0c70099914fcd063135da3c580865e924cunaffected
LinuxLinux5.4, 0, 5.10.248, 5.15.198, 6.1.161, 6.6.121, 6.12.66, 6.18.6, 6.19affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.