rootpwn

high · CVSS v3 7

CVE-2026-98030

The Linux kernel’s DSA BCM_SF2 driver contains a flaw that allows an attacker to trigger a buffer overflow when querying CFP rule lists via

Overview

The Linux kernel’s DSA BCM_SF2 driver contains a flaw that allows an attacker to trigger a buffer overflow when querying CFP rule lists via ETHTOOL_GRXCLSRLALL. The vulnerability can cause a kernel crash or memory corruption without requiring elevated privileges. It affects all systems running affected kernel versions that have CFP rules enabled.

Description

In the Linux kernel, the following vulnerability has been resolved: net: dsa: bcm_sf2: bound the CFP rule dump by the caller's buffer size bcm_sf2_cfp_rule_get_all() walks the whole cfp.unique bitmap into rule_locs[] without consulting nfc->rule_cnt, which is how many entries the caller had room for. ETHTOOL_GRXCLSRLALL requires no CAP_NET_ADMIN and the ioctl sizes the buffer from the rule_cnt userspace passes in, so once an admin has installed CFP rules any user can ask for fewer slots than there are rules and run off the end of the allocation. A rule_cnt of 0 leaves the buffer pointer NULL and the walk dereferences it.

Impact

The flaw compromises availability by enabling a denial‑of‑service through a kernel panic. It may also lead to integrity violations if the out‑of‑bounds write corrupts kernel memory. Confidentiality is not directly impacted. Defenders are the system administrators and security teams responsible for kernel maintenance.

Remediation

Apply the latest kernel update that patches bcm_sf2_cfp_rule_get_all to respect rule_cnt and guard against NULL pointers. If immediate patching is not possible, disable CFP rule management or restrict ETHTOOL_GRXCLSRLALL usage to privileged users only. Verify that CAP_NET_ADMIN is required for CFP operations and consider hardening via SELinux/AppArmor profiles.

Risk context

High severity (CVSS 7.0) indicates a significant risk. Although no EPSS data is available, the vulnerability can be exploited by any local user on systems with CFP rules configured, making it a priority for patching.

Affected products

  • Linux kernel
  • RedHat Enterprise Linux
  • Ubuntu
  • Debian
  • CentOS
  • Fedora
  • SUSE Linux Enterprise Server

Scores

Severity
high
CVSS v2
6
CVSS v3
7
CVSS v4
—
EPSS
—

kernel buffer-overflow ETHTOOL CFP high-severity Linux network-driver defense

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