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Collection Degraded30 / 46 Sources HealthyPublic Intel Only
Vulnerabilities/CVE-2021-22555Public Intelligence Dossier
Source: netapp · Limited verification•Last verified: •Collection Degraded
CVE-2021-22555ListedHIGH (raw)CVSS 8.3CWE-787

A heap out-of-bounds write affecting Linux since v2.6.19-rc1 was discovered in net/netfilter/x_tables.c

Published: 07 Jul 2021•Last updated: 13 Oct 2026, 11:55 PM IST•Source identifier: cve-coordination@google.com
Dossier completeness: source-provided sections 3 / 3 · rule guidance not available. Missing source facts count as incomplete.
Official source
CISA KEV catalog
Listed
Added06 Oct 2025
Due27 Oct 2025
RansomwareUnknown
CVSS score
8.3HIGH (raw)
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
Metric sourcecve-coordination@google.com
EPSS probability
78.7%0.787
Percentile100th
Weakness type
CWE-787
No further CWE recorded
Remediation
Patch status unknown
No fixed version or KB recorded

Why It Matters

Analysis dossier

Why It Matters

A heap out-of-bounds write affecting Linux since v2.6.19-rc1 was discovered in net/netfilter/x_tables.c. This allows an attacker to gain privileges or cause a DoS (via heap memory corruption) through user name space

SOC priority

Immediate Attention

Actively exploited

Yes

Publicly disclosed

Unknown

Risk basis: CISA KEV exploitation signal; SOC ecosystem technology relevance; HIGH severity; Known exploitation signal from CISA KEV or ransomware metadata

Affected Products & Remediation

21 source-backed products
Affected products and versions (source)
  • netapp c400 firmware · version range not provided by source · NVD CPE · Source
  • netapp c250 firmware · version range not provided by source · NVD CPE · Source
  • netapp h410c firmware · version range not provided by source · NVD CPE · Source
  • netapp h300s firmware · version range not provided by source · NVD CPE · Source
  • netapp h500s firmware · version range not provided by source · NVD CPE · Source
  • netapp h700s firmware · version range not provided by source · NVD CPE · Source
  • netapp h410s firmware · version range not provided by source · NVD CPE · Source
  • linux linux kernel · >= 2.6.19 < 4.4.267; >= 4.5 < 4.9.267; >= 4.10 < 4.14.231; >= 4.15 < 4.19.188; >= 4.20 < 5.4.113; >= 5.5 < 5.10.31; >= 5.11 < 5.12 · NVD CPE · Source
  • broadcom fabric operating system · version range not provided by source · NVD CPE · Source
  • netapp fas 8300 firmware · version range not provided by source · NVD CPE · Source
  • netapp fas 8700 firmware · version range not provided by source · NVD CPE · Source
  • netapp aff a400 firmware · version range not provided by source · NVD CPE · Source
  • netapp aff a250 firmware · version range not provided by source · NVD CPE · Source
  • netapp aff 500f firmware · version range not provided by source · NVD CPE · Source
  • netapp h610c firmware · version range not provided by source · NVD CPE · Source
  • netapp h610s firmware · version range not provided by source · NVD CPE · Source
  • netapp h615c firmware · version range not provided by source · NVD CPE · Source
  • netapp cloud backup · version range not provided by source · NVD CPE · Source
  • netapp hci management node · version range not provided by source · NVD CPE · Source
  • netapp solidfire · version range not provided by source · NVD CPE · Source
  • netapp solidfire baseboard management controller · version range not provided by source · NVD CPE · Source
NVD applicability prerequisites: cpe:2.3:h:netapp:c400:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:c250:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:h410c:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:h300s:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:h500s:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:h700s:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:h410s:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:fas_8300:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:fas_8700:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:aff_a400:-:*:*:*:*:*:*:*. These are conditions, not proof that an environment is exposed or unaffected.
Recorded patch / KBNot provided by source

Vendor or catalog guidance (source)

  • CISA KEV: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Known exploitation (source facts)

Only what a source states. Unknown means no source has said either way; it is not "not exploited".

CISA KEV
Listed
Exploited (source statement)
Yes
Publicly disclosed (source)
Unknown

CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Suggested hunting (rule-based inference)

SecOps Signal recommendation (rule-based inference). These steps are hunting hypotheses from the vulnerability class; they do not state or imply that exploitation occurred here or anywhere.

No rule-based guidance for this vulnerability class

CISA KEV Record

Catalog entry
06 Oct 2025
Required action due
27 Oct 2025
Known ransomware use
Unknown

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Change History & Source Data

— No recorded material change

CNA / source
cve-coordination@google.com
Record status · verification
UPDATED · CISA KEV confirmed
CPE
cpe:2.3:o:netapp:c400_firmware:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:c400:-:*:*:*:*:*:*:*, cpe:2.3:o:netapp:c250_firmware:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:c250:-:*:*:*:*:*:*:*, cpe:2.3:o:netapp:h410c_firmware:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:h410c:-:*:*:*:*:*:*:*, cpe:2.3:o:netapp:h300s_firmware:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:h300s:-:*:*:*:*:*:*:*, cpe:2.3:o:netapp:h500s_firmware:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:h500s:-:*:*:*:*:*:*:*

Evidence & Provenance

4 public sources
CISA KEV CatalogAdded 2025-10-06git.kernel.orgSource recordnvd.nist.govSource recordgit.kernel.orgSource record

Linked by the query's stored exact CVE association. Review required tables and validation status before use.

Detection Hunting Query
Target: DeviceTvmSoftwareVulnerabilities•Defender XDR
Detect endpoints exposed to CVE-2021-22555
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2021-22555
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2021-22555"| project DeviceId, DeviceName, OSPlatform, OSVersion, SoftwareVendor, SoftwareName, SoftwareVersion, CveId, VulnerabilitySeverityLevel, RecommendedSecurityUpdate, RecommendedSecurityUpdateId| sort by VulnerabilitySeverityLevel desc
Schema Checked · Not runtime validatedSource: SecOps Signal deterministic template · Limited verificationStatic screening: Passed structure and schema checks; tenant execution is not verified.
Open KQL Library

Correlated briefings

— No published briefing references this CVE

SecOps Signal surfaces public advisory facts only. A missing value means the source has not published it, not that your environment is unaffected. No tenant inventory is connected.