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NVD / CVE Program· CNA Linux

CVE-2021-47333: misc: alcor_pci: fix null-ptr-deref when there is no PCI bridge

MediumCVSS 5.5 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.23% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 09d154990ca82d14aed2b72796f6c8845e2e605d, 3ce3e45cc333da707d4d6eb433574b990bcc26f5, 58f69684ba03e5b0e0a3ae844a845280c0f06309.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 09d154990ca82d14aed2b72796f6c8845e2e605d, 3ce3e45cc333da707d4d6eb433574b990bcc26f5, 58f69684ba03e5b0e0a3ae844a845280c0f06309 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: misc: alcor_pci: fix null-ptr-deref when there is no PCI bridge There is an issue with the ASPM(optional) capability checking function. A device might be attached to root complex directly, in this case, bus->self(bridge) will be NULL, thus priv->parent_pdev is NULL. Since alcor_pci_init_check_aspm(priv->parent_pdev) checks the PCI link's ASPM capability and populate parent_cap_off, which will be used later by alcor_pci_aspm_ctrl() to dynamically turn on/off device, what we can do here is to avoid checking the capability if we are on the root complex. This will make pdev_cap_off 0 and alcor_pci_aspm_ctrl() will simply return when bring called, effectively disable ASPM for the device. [ 1.246492] BUG: kernel NULL pointer dereference, address: 00000000000000c0 [ 1.248731] RIP: 0010:pci_read_config_byte+0x5/0x40 [ 1.253998] Call Trace: [ 1.254131] ? alcor_pci_find_cap_offset.isra.0+0x3a/0x100 [alcor_pci] [ 1.254476] alcor_pci_probe+0x169/0x2d5 [alcor_pci]

Published
May 21, 2024
Updated
Jun 17, 2026
EPSS
0.2% · 15th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 5.0affected
    • 4f556bc04e3c0de2f5c69adc9e9f2bcefcad079d and later · before d2639ffdcad463b358b6bef8645ff81715daffcbaffected · git
    • 4f556bc04e3c0de2f5c69adc9e9f2bcefcad079d and later · before 58f69684ba03e5b0e0a3ae844a845280c0f06309affected · git
    • 4f556bc04e3c0de2f5c69adc9e9f2bcefcad079d and later · before 717cf5ae52322ddbdf3ac2c584b34c5970b0d174affected · git
    • 4f556bc04e3c0de2f5c69adc9e9f2bcefcad079d and later · before 09d154990ca82d14aed2b72796f6c8845e2e605daffected · git
    • 4f556bc04e3c0de2f5c69adc9e9f2bcefcad079d and later · before 3ce3e45cc333da707d4d6eb433574b990bcc26f5affected · git
    • before 5.0not affected · semver
    • 5.4.134 and later · up to and including 5.4.*not affected · semver
    • 5.10.52 and later · up to and including 5.10.*not affected · semver
    • 5.12.19 and later · up to and including 5.12.*not affected · semver
Affected versions · NVD (4)

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernelbefore 5.4.134
  • linux linux kernel5.5 and later · before 5.10.52
  • linux linux kernel5.11 and later · before 5.12.19
  • linux linux kernel5.13 and later · before 5.13.4

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 5.14.6-15.14.6-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe…KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2021-47331May 21, 2024 · usb: common: usb-conn-gpio: fix NULL pointer dereference of charger
    22Monitor
  • ← EarlierCVE-2021-47332May 21, 2024 · ALSA: usx2y: Don't call free_pages_exact() with NULL address
    22Monitor
  • Later →CVE-2021-47334May 21, 2024 · misc/libmasm/module: Fix two use after free in ibmasm_init_one
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux09d154990ca82d14aed2b72796f6c8845e2e605dVendor (CNA)
Linux Linux3ce3e45cc333da707d4d6eb433574b990bcc26f5Vendor (CNA)
Linux Linux58f69684ba03e5b0e0a3ae844a845280c0f06309Vendor (CNA)
Linux Linux717cf5ae52322ddbdf3ac2c584b34c5970b0d174Vendor (CNA)
Linux Linuxd2639ffdcad463b358b6bef8645ff81715daffcbVendor (CNA)
debian:linux5.14.6-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-476 · NULL Pointer Dereference

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

References

Show all references (4 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records