Risk Letters

Exploited vulnerability

CVE-2021-22555

TLP:CLEAR

Linux Kernel Heap Out-of-Bounds Write Vulnerability

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.

Facts

  • Vendor: Linux
  • Product: Kernel
  • CVSS: 8.3
  • EPSS (probability of exploitation within 30 days): 78.7 %
  • On CISA's Known Exploited Vulnerabilities list since: 6 October 2025
  • First known exploitation: 6 October 2025
  • CISA's deadline for US federal agencies: 27 October 2025
  • Weakness: CWE-787
  • First seen by Risk Letters: 6 October 2025

Members see which Nordic sectors the flaw hits, and what to do about it.

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Data: NVD (public domain), CISA KEV, FIRST EPSS, MITRE ATT&CK, AlienVault OTX. NVD