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bpf: NUL-terminate replaced sysctl value

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: bpf: NUL-terminate replaced sysctl value When writing to sysctls, proc_sys_call_handler() guarantees that the buffer passed to proc handlers is NUL-terminated. If bpf_sysctl_set_new_value() replaces the pending sysctl value, it can hand a replacement buffer directly to proc handlers. However, the helper currently copies only buf_len bytes into that buffer without appending a NUL terminator, leaving downstream parsers vulnerable to out-of-bounds access. Fix this by appending a '\0' after the replaced value to restore the expected sysctl semantics. Since the helper already rejects buf_len greater than PAGE_SIZE - 1, there is always room for the extra byte. Reproduced in a QEMU x86_64 guest booted with KASAN while exercising the sysctl replacement path with a cgroup/sysctl BPF program. The reproducer targets `/proc/sys/net/core/flow_limit_cpu_bitmap`, fills the original user write buffer with non-zero bytes, and overrides the sysctl value so the replacement buffer lacks a terminating NUL. Under that setup, the pre-fix kernel reported: BUG: KASAN: slab-out-of-bounds in strnchrnul+0x72/0x90 Read of size 1 at addr ffff88800de57000 by task repro_patch3/66 CPU: 0 UID: 0 PID: 66 Comm: repro_patch3 Not tainted 7.1.0-rc3-00269-g8370ca1f87cc #6 PREEMPT(lazy) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 Call Trace: dump_stack_lvl+0x68/0xa0 print_report+0xcb/0x5e0 ? __virt_addr_valid+0x21

Announced Source revision 1
Original source ↗

CVE-2026-97420

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-97420

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "32927393dc1ccd60fb2bdc05b9e8e88753761469",
        "lessThan": "bfcee1f79aaefa90679ad47690107fb7682724ec",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "32927393dc1ccd60fb2bdc05b9e8e88753761469",
        "lessThan": "c73e4a04eedc677fe91a736d7a5db45100adba5e",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "32927393dc1ccd60fb2bdc05b9e8e88753761469",
        "lessThan": "36d3e9f62dc2beb9299d3bb6f589cb9e07f773fe",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "32927393dc1ccd60fb2bdc05b9e8e88753761469",
        "lessThan": "31377675c3d75603d957c08e338a9ac27e9f6cd5",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "32927393dc1ccd60fb2bdc05b9e8e88753761469",
        "lessThan": "76c14b10f50eb0afcc76e244562fa2d8c661e224",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "32927393dc1ccd60fb2bdc05b9e8e88753761469",
        "lessThan": "3b2814dd842a565fcf9cc370156e1ba9eae16239",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "32927393dc1ccd60fb2bdc05b9e8e88753761469",
        "lessThan": "a66e3b5bacf38d6ab29fa05a9754f7a114485605",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "kernel/bpf/cgroup.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.8"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.8",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.271",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.222",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.189",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.158",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.111",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.53",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "kernel/bpf/cgroup.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-97420

Source reference: /cveMetadata/cveId

Publisher severity

No explicit severity was provided.

Event
#8311 · Revision 1
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Publisher date
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