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Findings

CVE-2021-22555

Linux Kernel Heap Out-of-Bounds Write Vulnerability

Published Jul 7, 2021 · updated Oct 13, 2026 · Linux Kernel

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

Timeline

Detection, updates, and resolution for this record.

  1. Jul 7, 2021 · Catalog

    Detected

    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

  2. Oct 6, 2025 · CISA KEV

    Known exploited

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

  3. Oct 27, 2025 · CISA KEV

    Remediation due

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

  4. Oct 13, 2026 · Catalog

    Updated

    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

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.

CISA due date Oct 27, 2025

Affected

  • cpe broadcom/fabric operating systemversion unspecified
  • cpe linux/linux kernelversion unspecified
  • cpe netapp/aff a400 firmwareversion unspecified
  • cpe netapp/c250 firmwareversion unspecified
  • cpe netapp/c400 firmwareversion unspecified
  • cpe netapp/fas 8300 firmwareversion unspecified
  • cpe netapp/fas 8700 firmwareversion unspecified
  • cpe netapp/h300s firmwareversion unspecified
  • cpe netapp/h410c firmwareversion unspecified
  • cpe netapp/h410s firmwareversion unspecified
  • cpe netapp/h500s firmwareversion unspecified
  • cpe netapp/h700s firmwareversion unspecified
  • vendor Linux Kernelversion unspecified

Sources

  • CISA KEVCVE-2021-22555

    Linux Kernel contains a heap out-of-bounds write vulnerability that could allow an attacker to gain privileges or cause a DoS (via heap memory corruption) through user name space.

    cisa.gov
  • CVE.orgCVE-2021-22555

    Official CVE identifier

    cve.org
  • FIRST EPSSCVE-2021-22555

    30-day exploitation probability 78.7%

    first.org
  • Exploit Database50135

    Public archive entry. The exploit body is not stored here.

    exploit-db.com
  • Metasploit Modulesexploit_linux/local/netfilter_xtables_heap_oob_write_priv_esc

    Public module reference (great). Module source is not copied into this catalog.

    rapid7.com
  • NIST NVDCVE-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

    nvd.nist.gov
  • Packet Storm Securityhttp://packetstormsecurity.com/files/163528/Linux-Kernel-Netfilter-Heap-Out-Of-Bounds-Write.html

    Packet Storm link already published on the finding.

    packetstormsecurity.com
  • Packet Storm Securityhttp://packetstormsecurity.com/files/163878/Kernel-Live-Patch-Security-Notice-LSN-0080-1.html

    Packet Storm link already published on the finding.

    packetstormsecurity.com
  • Packet Storm Securityhttp://packetstormsecurity.com/files/164155/Kernel-Live-Patch-Security-Notice-LSN-0081-1.html

    Packet Storm link already published on the finding.

    packetstormsecurity.com
  • Packet Storm Securityhttp://packetstormsecurity.com/files/164437/Netfilter-x_tables-Heap-Out-Of-Bounds-Write-Privilege-Escalation.html

    Packet Storm link already published on the finding.

    packetstormsecurity.com

References