Red Hat Security Advisory: kernel security update

Fixed packages 49

Vulnerabilities 3

• High 8.1
  CVE-2025-40186

  tcp: Don't call reqsk_fastopen_remove() in tcp_conn_request().

  In the Linux kernel, the following vulnerability has been resolved: tcp: Don't call reqsk_fastopen_remove() in tcp_conn_request(). syzbot reported the splat below in tcp_conn_request(). [0] If a listener is close()d while a TFO socket is being processed in tc…

  Linux Linux linux-raspi2 linux-hwe Linux Debian Ubuntu
  Nov 12, 2025
• Medium 4.7
  CVE-2023-53401

  mm: kmem: fix a NULL pointer dereference in obj_stock_flush_required()

  In the Linux kernel, the following vulnerability has been resolved: mm: kmem: fix a NULL pointer dereference in obj_stock_flush_required() KCSAN found an issue in obj_stock_flush_required(): stock->cached_objcg can be reset between the check and dereference: …

  Linux Linux linux-raspi2 linux-hwe Linux Debian Ubuntu Azure Linux
  Sep 18, 2025
• Unscored —
  CVE-2025-39955

  tcp: Clear tcp_sk(sk)->fastopen_rsk in tcp_disconnect().

  In the Linux kernel, the following vulnerability has been resolved: tcp: Clear tcp_sk(sk)->fastopen_rsk in tcp_disconnect(). syzbot reported the splat below where a socket had tcp_sk(sk)->fastopen_rsk in the TCP_ESTABLISHED state. [0] syzbot reused the server…

  Linux Linux linux-raspi2 linux-hwe Linux Debian Ubuntu Azure Linux
  Oct 9, 2025

References

• article
  https://access.redhat.com/security/updates/classification/#important
• report
  https://bugzilla.redhat.com/show_bug.cgi?id=2396417
• report
  https://bugzilla.redhat.com/show_bug.cgi?id=2402699
• report
  https://bugzilla.redhat.com/show_bug.cgi?id=2414724
• advisory
  https://security.access.redhat.com/data/csaf/v2/advisories/2025/rhsa-2025_23427.json
• report
  https://access.redhat.com/security/cve/CVE-2023-53401
• advisory
  https://www.cve.org/CVERecord?id=CVE-2023-53401
• advisory
  https://nvd.nist.gov/vuln/detail/CVE-2023-53401
• article
  https://lore.kernel.org/linux-cve-announce/2025091800-CVE-2023-53401-b668@gregkh/T
• report
  https://access.redhat.com/security/cve/CVE-2025-39955
• advisory
  https://www.cve.org/CVERecord?id=CVE-2025-39955
• advisory
  https://nvd.nist.gov/vuln/detail/CVE-2025-39955
• article
  https://lore.kernel.org/linux-cve-announce/2025100942-CVE-2025-39955-f36b@gregkh/T
• report
  https://access.redhat.com/security/cve/CVE-2025-40186
• advisory
  https://www.cve.org/CVERecord?id=CVE-2025-40186
• advisory
  https://nvd.nist.gov/vuln/detail/CVE-2025-40186
• article
  https://lore.kernel.org/linux-cve-announce/2025111244-CVE-2025-40186-b204@gregkh/T