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CVE-2026-72111 (GCVE-0-2026-72111)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:52 – Updated: 2026-08-17 05:40
VLAI
Title
bpf: Reset register bounds before narrowing retval range in check_mem_access()
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Reset register bounds before narrowing retval range in check_mem_access() When the BPF verifier processes a context load of an LSM hook return value, it calls __mark_reg_s32_range() to narrow the register to the hook's valid range. However, __mark_reg_s32_range() intersects the new range with the register's existing bounds using max_t()/min_t() rather than replacing them. If the destination register carries stale bounds from a prior instruction (e.g. BPF_MOV64_IMM), the intersection can produce a range narrower than reality. The verifier then believes it knows the register's exact value, while at runtime the actual hook return value is loaded, creating a verifier/runtime mismatch that can be used to bypass BPF memory safety checks. The else branch already calls mark_reg_unknown() to reset register state before any narrowing. Apply the same reset in the is_retval path so stale bounds are cleared before __mark_reg_s32_range() intersects.
Severity
8.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 5d99e198be279045e6ecefe220f5c52f8ce9bfd5 , < bde92f65042ec14389782dd223f706bf6b59ce5d (git)
Affected: 5d99e198be279045e6ecefe220f5c52f8ce9bfd5 , < 0993dc5fc619c0b25ab1310cb11d65e78351c0fe (git)
Affected: 5d99e198be279045e6ecefe220f5c52f8ce9bfd5 , < 5a55f9aecc08990940e70f0c7048a80850c5a16a (git)
Affected: 5d99e198be279045e6ecefe220f5c52f8ce9bfd5 , < 5e0b273e0a62cc04ec338c7b502797c66c2ed42a (git)
Affected: 1050727d83e70449991c29dd1cf29fe936a63da3 (git)
Affected: 27ca3e20fe80be85a92b10064dfeb56cb2564b1c (git)
Affected: 6.10.13 , < 6.11 (semver)
Affected: 6.11.2 , < 6.12 (semver)
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Linux Linux Affected: 6.12
Unaffected: 0 , < 6.12 (semver)
Unaffected: 6.12.103 , ≤ 6.12.* (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reset register bounds before narrowing retval range in check_mem_access()\n\nWhen the BPF verifier processes a context load of an LSM hook return\nvalue, it calls __mark_reg_s32_range() to narrow the register to the\nhook\u0027s valid range. However, __mark_reg_s32_range() intersects the new\nrange with the register\u0027s existing bounds using max_t()/min_t() rather\nthan replacing them.\n\nIf the destination register carries stale bounds from a prior instruction\n(e.g. BPF_MOV64_IMM), the intersection can produce a range narrower than\nreality. The verifier then believes it knows the register\u0027s exact value,\nwhile at runtime the actual hook return value is loaded, creating a\nverifier/runtime mismatch that can be used to bypass BPF memory safety\nchecks.\n\nThe else branch already calls mark_reg_unknown() to reset register state\nbefore any narrowing. Apply the same reset in the is_retval path so\nstale bounds are cleared before __mark_reg_s32_range() intersects."
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            }
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        "shortName": "Linux"
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    "cveId": "CVE-2026-72111",
    "datePublished": "2026-08-15T05:52:52.538Z",
    "dateReserved": "2026-08-09T03:40:39.906Z",
    "dateUpdated": "2026-08-17T05:40:25.647Z",
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      "date": "2026-09-05",
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    },
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-17T22:30:40+00:00",
      "cve": "CVE-2026-72111",
      "id": "CVE-2026-72111",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: bpf: Reset register bounds before narrowing retval range in check_mem_access()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72111.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.