CVE-2021-46963

Kernel crash via upper-layer request free

Published Feb 27, 2024 · Updated Aug 5, 2026

Use-after-free in the Linux qla2xxx SCSI driver allows local users to crash the kernel through I/O to a QLogic Fibre Channel adapter. qla2xxx_mqueuecommand incorrectly frees an SRB allocated and owned by the upper SCSI layer when the full-mempool path handles a request. Exploitation requires access to a filesystem or block device backed by a qla2xxx HBA; the unintended free can corrupt kernel memory and panic the host.

CVSS severity8.8
High
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the Linux qla2xxx SCSI driver allows local users to crash the kernel through I/O to a QLogic Fibre Channel adapter. qla2xxx_mqueuecommand incorrectly frees an SRB allocated and owned by the upper SCSI layer when the full-mempool path handles a request. Exploitation requires access to a filesystem or block device backed by a qla2xxx HBA; the unintended free can corrupt kernel memory and panic the host.

The record

CVE
CVE-2021-46963
Published
Feb 27, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 27, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.19.90 <4.19.191
  2. Affected versionversion=4a1cc2f71bc57cf8dee6f58e7d2355a43aabb312
  3. Affected versionversion=5.3.17 <5.4
  4. Affected versionversion=5.4.4 <5.4.118
  5. Affected versionversion=5.5
  6. Affected versionversion=64a8c5018a4b21b04a756a56c495ef47c14e92d9 <c5ab9b67d8b061de74e2ca51bf787ee599bd7f89
  7. Affected versionversion=af2a0c51b1205327f55a7e82e530403ae1d42cbb <6641df81ab799f28a5d564f860233dd26cca0d93
  8. Affected versionversion=af2a0c51b1205327f55a7e82e530403ae1d42cbb <702cdaa2c6283c135ef16d52e0e4e3c1005aa538
  9. Affected versionversion=af2a0c51b1205327f55a7e82e530403ae1d42cbb <80ef24175df2cba3860d0369d1c662b49ee2de56
  10. Affected versionversion=af2a0c51b1205327f55a7e82e530403ae1d42cbb <a73208e3244127ef9f2cdf24e4adb947aaa32053
  11. Affected versionversion=dea6ee7173039d489977c9ed92e3749154615db4 <77509a238547863040a42d57c72403f7d4c89a8f

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.19.90 <4.19.191; version=4a1cc2f71bc57cf8dee6f58e7d2355a43aabb312; version=5.3.17 <5.4; version=5.4.4 <5.4.118; version=5.5; version=64a8c5018a4b21b04a756a56c495ef47c14e92d9 <c5ab9b67d8b061de74e2ca51bf787ee599bd7f89; version=af2a0c51b1205327f55a7e82e530403ae1d42cbb <6641df81ab799f28a5d564f860233dd26cca0d93; version=af2a0c51b1205327f55a7e82e530403ae1d42cbb <702cdaa2c6283c135ef16d52e0e4e3c1005aa538; version=af2a0c51b1205327f55a7e82e530403ae1d42cbb <80ef24175df2cba3860d0369d1c662b49ee2de56; version=af2a0c51b1205327f55a7e82e530403ae1d42cbb <a73208e3244127ef9f2cdf24e4adb947aaa32053; version=dea6ee7173039d489977c9ed92e3749154615db4 <77509a238547863040a42d57c72403f7d4c89a8f

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
8.8Linux CNACVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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