How severe is CVE-2021-22555?

CVE-2021-22555 has a CVSS 3.x base score of 8.3, rated high severity. It is exploitable over an adjacent network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-22555 being actively exploited?

Yes. CVE-2021-22555 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2025-10-06, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2021-22555?

CVE-2021-22555 primarily affects Netapp Cloud Backup. In total, 21 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-22555?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2021-22555 have an EU (EUVD) identifier?

Yes. CVE-2021-22555 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-9696. It is also flagged as exploited in the EUVD (since 2025-10-06).

When was CVE-2021-22555 published?

CVE-2021-22555 was published on 2021-07-07 and last updated on 2026-06-17.

CVE-2021-22555

CVE-2021-22555 is a high-severity vulnerability in Netapp Cloud Backup with a CVSS 3.x base score of 8.3. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2025-10-06). The underlying weakness is classified as CWE-787.

Key facts

Severity: High (CVSS 3.x base score 8.3)
CVSS v2: 4.6
EPSS exploit prediction: 79% (100th percentile)
Actively exploited: Yes — listed in CISA KEV (added 2025-10-06)
EU (EUVD) id: EUVD-2021-9696
EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2025-10-06)
Weakness: CWE-787
Affected product: Netapp Cloud Backup
Published: 2021-07-07
Last modified: 2026-06-17

Description

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

Frequently asked questions

What is CVE-2021-22555?: 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
How severe is CVE-2021-22555?: CVE-2021-22555 has a CVSS 3.x base score of 8.3, rated high severity. It is exploitable over an adjacent network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-22555 being actively exploited?: Yes. CVE-2021-22555 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2025-10-06, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2021-22555?: CVE-2021-22555 primarily affects Netapp Cloud Backup. In total, 21 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-22555?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2021-22555 have an EU (EUVD) identifier?: Yes. CVE-2021-22555 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-9696. It is also flagged as exploited in the EUVD (since 2025-10-06).
When was CVE-2021-22555 published?: CVE-2021-22555 was published on 2021-07-07 and last updated on 2026-06-17.

References

Affected products (21)

cpe:2.3:o:netapp:c400_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:c250_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:h410c_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:h300s_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:h500s_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:h700s_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:h410s_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:brocade:fabric_operating_system:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:fas_8300_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:fas_8700_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:aff_a400_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:aff_a250_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:aff_500f_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:h610c_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:h610s_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:netapp:h615c_firmware:-:*:*:*:*:*:*:*
cpe:2.3:a:netapp:cloud_backup:-:*:*:*:*:*:*:*
cpe:2.3:a:netapp:hci_management_node:-:*:*:*:*:*:*:*
cpe:2.3:a:netapp:solidfire:-:*:*:*:*:*:*:*
cpe:2.3:a:netapp:solidfire_baseboard_management_controller:*:*:*:*:*:*:*:*

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