CVE-2021-46964

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

Score 5.5 from GitHub Security Advisory published 2024-02-27. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
5.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.5Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

In the Linux kernel, the following vulnerability has been resolved:

scsi: qla2xxx: Reserve extra IRQ vectors

Commit a6dcfe08487e ("scsi: qla2xxx: Limit interrupt vectors to number of CPUs") lowers the number of allocated MSI-X vectors to the number of CPUs.

That breaks vector allocation assumptions in qla83xx_iospace_config(), qla24xx_enable_msix() and qla2x00_iospace_config(). Either of the functions computes maximum number of qpairs as:

ha->max_qpairs = ha->msix_count - 1 (MB interrupt) - 1 (default response queue) - 1 (ATIO, in dual or pure target mode)

max_qpairs is set to zero in case of two CPUs and initiator mode. The number is then used to allocate ha->queue_pair_map inside qla2x00_alloc_queues(). No allocation happens and ha->queue_pair_map is left NULL but the driver thinks there are queue pairs available.

qla2xxx_queuecommand() tries to find a qpair in the map and crashes:

if (ha->mqenable) { uint32_t tag; uint16_t hwq; struct qla_qpair *qpair = NULL;

tag = blk_mq_unique_tag(cmd->request); hwq = blk_mq_unique_tag_to_hwq(tag); qpair = ha->queue_pair_map[hwq]; # <- HERE

if (qpair) return qla2xxx_mqueuecommand(host, cmd, qpair); }

BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] SMP PTI CPU: 0 PID: 72 Comm: kworker/u4:3 Tainted: G W 5.10.0-rc1+ #25 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014 Workqueue: scsi_wq_7 fc_scsi_scan_rport [scsi_transport_fc] RIP: 0010:qla2xxx_queuecommand+0x16b/0x3f0 [qla2xxx] Call Trace: scsi_queue_rq+0x58c/0xa60 blk_mq_dispatch_rq_list+0x2b7/0x6f0 ? __sbitmap_get_word+0x2a/0x80 __blk_mq_sched_dispatch_requests+0xb8/0x170 blk_mq_sched_dispatch_requests+0x2b/0x50 __blk_mq_run_hw_queue+0x49/0xb0 __blk_mq_delay_run_hw_queue+0xfb/0x150 blk_mq_sched_insert_request+0xbe/0x110 blk_execute_rq+0x45/0x70 __scsi_execute+0x10e/0x250 scsi_probe_and_add_lun+0x228/0xda0 __scsi_scan_target+0xf4/0x620 ? __pm_runtime_resume+0x4f/0x70 scsi_scan_target+0x100/0x110 fc_scsi_scan_rport+0xa1/0xb0 [scsi_transport_fc] process_one_work+0x1ea/0x3b0 worker_thread+0x28/0x3b0 ? process_one_work+0x3b0/0x3b0 kthread+0x112/0x130 ? kthread_park+0x80/0x80 ret_from_fork+0x22/0x30

The driver should allocate enough vectors to provide every CPU it's own HW queue and still handle reserved (MB, RSP, ATIO) interrupts.

The change fixes the crash on dual core VM and prevents unbalanced QP allocation where nr_hw_queues is two less than the number of CPUs.

CVSS v3
5.5
EG Score
5.5(medium)
EG Risk
25(Track)
EG Risk 25/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity55% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
13%
KEV
Not listed

Published

February 27, 2024

Last Modified

January 8, 2025

References (6)

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 11× in last 7d / 43× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 103 total refreshes for this CVE.

  1. 2026-07-26 14:52 UTCEPSS rescore
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Frequently asked(5)

What is CVE-2021-46964?
CVE-2021-46964 is a medium vulnerability published on February 27, 2024. In the Linux kernel, the following vulnerability has been resolved: scsi: qla2xxx: Reserve extra IRQ vectors Commit a6dcfe08487e ("scsi: qla2xxx: Limit interrupt vectors to number of CPUs") lowers the number of allocated MSI-X vectors to the number of CPUs. That breaks vector allocation assumptions…
When was CVE-2021-46964 disclosed?
CVE-2021-46964 was first published in the National Vulnerability Database on February 27, 2024, with the most recent update on January 8, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-46964 actively exploited?
CVE-2021-46964 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 86.7% of all scored CVEs.
What is the CVSS score of CVE-2021-46964?
CVE-2021-46964 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2021-46964?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-46964, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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