Security readout for executives and security teams
Plain-English summary
A race condition in Linux netfilter queue handling can let one processor access an entry after another processor frees it. This may crash the kernel and, according to the supplied CVSS assessment, could affect confidentiality, integrity, and availability. Exploitation requires local, low-privileged access; no user interaction is required.
Executive priority
Treat as a high-priority kernel maintenance issue on exposed shared hosts and network-security systems. Schedule prompt patching through normal emergency-change processes, while confirming actual nfnetlink_queue use. Immediate crisis response is not supported because active exploitation is not evidenced and remote exploitation is not indicated.
Technical view
The nfnetlink_queue subsystem shared a global hash table across queues. Concurrent verdict processing could traverse an nf_queue_entry after another CPU freed it, causing a slab use-after-free in nfqnl_recv_verdict. The fix makes the hash table queue-specific, preventing unsafe cross-queue access without adding per-packet RCU memory pressure.
Likely exposure
Potential exposure is limited to Linux hosts running an affected kernel and using nfnetlink_queue functionality. The bundle identifies fixed commits and lists 6.12.75, 6.18.14, and 6.19.4 as unaffected, but does not provide complete vulnerable version ranges. Distribution package status must therefore be checked directly.
Exploitation context
The CVSS vector indicates local access, low complexity, low privileges, and no user interaction. The CVE is not listed as KEV, and the supplied sources provide no evidence of active exploitation or a public exploit. Practical exploitability beyond triggering a kernel crash is not established here.
Researcher notes
The source demonstrates a concurrent lifetime-management flaw involving a globally shared hash table. Queue-local tables are the selected remediation; kfree_rcu was considered but rejected because per-packet allocation would increase memory pressure. Exact introduction points and vulnerable release ranges are absent from the bundle, so commit ancestry and distribution backports require verification.
Mitigation direction
- Update to a vendor-supported kernel containing the applicable upstream stable fix.
- Confirm distribution advisories or package changelogs map the installed kernel to CVE-2026-43084.
- Prioritize multi-user, container-hosting, or security-gateway systems that use nfnetlink_queue.
- If updating is delayed, consult vendor guidance about safely limiting nfnetlink_queue availability.
Validation and detection
- Inventory running kernel versions, not only installed kernel packages.
- Determine whether nfnetlink_queue is loaded or required by firewall and packet-inspection workloads.
- Verify the kernel package includes one of the cited fixes or an equivalent backport.
- Reboot after updating and confirm the running kernel is the remediated build.
- Review kernel logs for nfqnl_recv_verdict crashes or use-after-free diagnostics.
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-2026-43084 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
- 7.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9LinuxVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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/22730cb96093b5be0609063bbb1923dbecd61252CVE reference, Linux
- https://git.kernel.org/stable/c/41e3652a178cb0eecd48e0e6e27fbb73a004046aCVE reference, Linux
- https://git.kernel.org/stable/c/9e5ebef91120d2764aefe557c3a484b6288f341fCVE reference, Linux
- https://git.kernel.org/stable/c/936206e3f6ff411581e615e930263d6f8b78df9dCVE 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.