Security readout for executives and security teams
Plain-English summary
This is a Linux kernel availability bug in the mISDN NetJet ISDN driver. Under a specific local failure path, the kernel can try to free an IRQ it never requested, causing a warning and possible panic. Business impact is service disruption, not data theft or code execution based on the provided sources.
Executive priority
Treat as a moderate availability risk. Prioritize normal kernel patching for systems with relevant ISDN driver exposure, and escalate only if affected kernels are used on high-availability systems where local users can trigger driver initialization.
Technical view
The flaw is in netjet.c nj_probe cleanup. If nj_setup fails with -EIO after card->irq is set, nj_release may call free_irq for an IRQ not successfully requested. The fix moves irq assignment to the request_irq path. CVSS is 4.7: local, high complexity, low privileges, availability impact only.
Likely exposure
Exposure is likely limited to Linux systems running affected kernels with the mISDN NetJet driver present and reachable through local device or driver initialization paths. Systems without this driver, hardware, or module path are less likely to be affected.
Exploitation context
The source bundle does not show active exploitation, and KEV is false. The CVSS vector indicates local access, high attack complexity, and low privileges. Evidence supports a denial-of-service crash scenario, especially where panic_on_warn or similar operational settings convert the warning into a panic.
Researcher notes
The evidence is a resolved Linux kernel cleanup bug with KASAN output and multiple stable commit references. The bundle does not provide exploit reports, affected distribution package names, or a standalone mitigation beyond applying fixed kernels or vendor guidance.
Mitigation direction
- Update to a vendor kernel that includes the referenced stable Linux fixes.
- Check distribution advisories for the exact fixed package or backport status.
- If unused, review vendor-supported options to disable mISDN NetJet support.
- Do not test crash behavior on production systems.
Validation and detection
- Inventory Linux kernel versions across systems that may include mISDN NetJet support.
- Confirm whether the mISDN NetJet driver is built, installed, or loadable.
- Verify the running kernel contains a vendor backport of the stable fix.
- Review kernel logs for nj_probe, nj_release, free_irq, or panic_on_warn events.
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
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ATT&CK lookup starting points
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CWE-400: Exact CWE lookup
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Open ATT&CK lookupCVE-2021-47284 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/958cb1078ca60d214826fd90a0961a447fade59aCVE reference, Linux
- https://git.kernel.org/stable/c/4c1fcb6ec964b44edbf84235134582a5ffae1521CVE reference, Linux
- https://git.kernel.org/stable/c/a0a37e4454ca1c0b424edc2c9c2487c2c46a1be6CVE reference, Linux
- https://git.kernel.org/stable/c/bf78e25bd3f487208e042c67c8a31706c2dba265CVE reference, Linux
- https://git.kernel.org/stable/c/9d7d4649dc1c53acf76df260fd519db698ed20d7CVE reference, Linux
- https://git.kernel.org/stable/c/143fc7220961220eecc04669e5909af8847bf8c8CVE reference, Linux
- https://git.kernel.org/stable/c/6249193e03709ea625e10706ecaf17fea0427d3dCVE reference, Linux
- https://git.kernel.org/stable/c/9f6f852550d0e1b7735651228116ae9d300f69b3CVE 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.
Uncontrolled Resource Consumption
Uncontrolled Resource Consumption represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.