What is CVE-2021-22555?

CVE-2021-22555 is a high-severity vulnerability in Broadcom Fabric Operating System, classified under Out-of-bounds Write. CVSS score: 8.3/10. Published 2021-07-07.

How severe is CVE-2021-22555?

High severity. CVSS v3 base score is 8.3 out of 10.

Is CVE-2021-22555 known to be exploited?

Yes. CVE-2021-22555 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-10-06), indicating it is being actively exploited. 125 public proof-of-concept repositories are indexed.

Buffer overflow in Broadcom Fabric Operating System

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

Vulnerability class: Buffer Overflow

Published 2021-07-07 · last modified 2026-10-13.

CVSS v3 metric

CVSS v3 base score 8.3 (High). Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.787 (99.6th percentile), scored 2026-10-19.

High probability of exploitation in the next 30 days — patch promptly. 100th percentile — 99.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.787 · newest: 0.787 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2025-10-06. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2025-10-27.

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.

Public proof-of-concept exploits

References

github.com/google/security-research/security/advisories/GHSA-xxx5-8mvq-3528 (Exploit, Third Party Advisory)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter… (Patch, Mailing List, Vendor Advisory)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/net/netfilter… (Patch, Mailing List, Vendor Advisory)
packetstormsecurity.com/files/163528/Linux-Kernel-Netfilter-Heap-Out-Of-Bounds-… (VDB Entry, Third Party Advisory)
security.netapp.com/advisory/ntap-20210805-0010/ (Third Party Advisory)
packetstormsecurity.com/files/163878/Kernel-Live-Patch-Security-Notice-LSN-0080… (Exploit, VDB Entry, Third Party Advisory)
packetstormsecurity.com/files/164155/Kernel-Live-Patch-Security-Notice-LSN-0081… (Exploit, VDB Entry, Third Party Advisory)
packetstormsecurity.com/files/164437/Netfilter-x_tables-Heap-Out-Of-Bounds-Writ… (Exploit, VDB Entry, Third Party Advisory)
packetstormsecurity.com/files/165477/Kernel-Live-Patch-Security-Notice-LSN-0083… (Exploit, VDB Entry, Third Party Advisory)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)

Frequently asked questions

What is CVE-2021-22555?: CVE-2021-22555 is a high-severity vulnerability in Broadcom Fabric Operating System, classified under Out-of-bounds Write. CVSS score: 8.3/10. Published 2021-07-07.
How severe is CVE-2021-22555?: High severity. CVSS v3 base score is 8.3 out of 10.
Is CVE-2021-22555 known to be exploited?: Yes. CVE-2021-22555 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-10-06), indicating it is being actively exploited. 125 public proof-of-concept repositories are indexed.