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CVE-2026-72338 (GCVE-0-2026-72338)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:55 – Updated: 2026-08-17 05:42
VLAI
Title
net/sched: act_pedit: fix TOCTOU heap OOB write in tc offload
Summary
In the Linux kernel, the following vulnerability has been resolved: net/sched: act_pedit: fix TOCTOU heap OOB write in tc offload There is a TOCTOU race condition in flower lockless approach between sizing a flow_rule buffer and filling it. zdi-disclosures@trendmicro.com reports: The cls_flower classifier operates with TCF_PROTO_OPS_DOIT_UNLOCKED (fl_change runs without RTNL), while RTM_NEWACTION holds RTNL, so the independent locking domains make the race reachable in practice. KASAN confirms: BUG: KASAN: slab-out-of-bounds in tcf_pedit_offload_act_setup+0x81b/0x930 Write of size 4 at addr ffff888001f27520 by task poc-toctou/312 The buggy address is located 0 bytes to the right of allocated 288-byte region [ffff888001f27400, ffff888001f27520) (cache kmalloc-512) Note: The result is a heap OOB write attacker-controlled content into the adjacent slab object (requires CAP_NET_ADMIN). The fix introduces reading tcfp_nkeys under act->tcfa_lock in all places using a new tcf_pedit_nkeys_locked() which replaces the old tcf_pedit_nkeys(). Additionally we close the remaining TOCTOU window between the sizing read and the fill reads by more careful accounting. Rather than silently truncating the key count, which leads to incorrect action semantics offloaded to hardware and secondary OOB writes if the remaining capacity is zero or consumed by prior actions, we enforce remaining capacity checks and return -ENOSPC if the required space exceeds the remaining capacity.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 71d0ed7079dffbc5cd0941d77d9b84e04109c9bb , < 0d8532a5e972a5351cf4ee4a435e0d65cbba8f23 (git)
Affected: 71d0ed7079dffbc5cd0941d77d9b84e04109c9bb , < 27488e1a7f19757e6146edca9458ed4ffc545557 (git)
Affected: 71d0ed7079dffbc5cd0941d77d9b84e04109c9bb , < 6f9b23eb92a894ae1118893996943990ee0b860e (git)
Affected: 71d0ed7079dffbc5cd0941d77d9b84e04109c9bb , < 8e49cd891bda447c68122d672510a604a8bb6b24 (git)
Affected: 71d0ed7079dffbc5cd0941d77d9b84e04109c9bb , < 8b519cbcabe836a441369fbec1a8a6518a709251 (git)
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Linux Linux Affected: 4.11
Unaffected: 0 , < 4.11 (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (semver)
Unaffected: 6.12.97 , ≤ 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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{
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    "cveId": "CVE-2026-72338",
    "datePublished": "2026-08-15T05:55:45.823Z",
    "dateReserved": "2026-08-09T03:40:39.920Z",
    "dateUpdated": "2026-08-17T05:42:56.770Z",
    "state": "PUBLISHED"
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KASAN\\nconfirms:\\n  BUG: KASAN: slab-out-of-bounds in tcf_pedit_offload_act_setup+0x81b/0x930\\n  Write of size 4 at addr ffff888001f27520 by task poc-toctou/312\\n  The buggy address is located 0 bytes to the right of\\n   allocated 288-byte region [ffff888001f27400, ffff888001f27520)\\n   (cache kmalloc-512)\\n\\nNote: The result is a heap OOB write attacker-controlled content into the\\nadjacent slab object (requires CAP_NET_ADMIN).\\n\\nThe fix introduces reading tcfp_nkeys under act-\u003etcfa_lock in all places\\nusing a new tcf_pedit_nkeys_locked() which replaces the old tcf_pedit_nkeys().\\nAdditionally we close the remaining TOCTOU window between the sizing read and\\nthe fill reads by more careful accounting.\\nRather than silently truncating the key count, which leads to incorrect\\naction semantics offloaded to hardware and secondary OOB writes if\\nthe remaining capacity is zero or consumed by prior actions, we enforce\\nremaining capacity checks and return -ENOSPC if the required space exceeds\\nthe remaining capacity.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"include/net/tc_act/tc_pedit.h\",\"net/sched/act_api.c\",\"net/sched/act_pedit.c\",\"net/sched/cls_api.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"71d0ed7079dffbc5cd0941d77d9b84e04109c9bb\",\"lessThan\":\"0d8532a5e972a5351cf4ee4a435e0d65cbba8f23\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"71d0ed7079dffbc5cd0941d77d9b84e04109c9bb\",\"lessThan\":\"27488e1a7f19757e6146edca9458ed4ffc545557\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"71d0ed7079dffbc5cd0941d77d9b84e04109c9bb\",\"lessThan\":\"6f9b23eb92a894ae1118893996943990ee0b860e\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"71d0ed7079dffbc5cd0941d77d9b84e04109c9bb\",\"lessThan\":\"8e49cd891bda447c68122d672510a604a8bb6b24\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"71d0ed7079dffbc5cd0941d77d9b84e04109c9bb\",\"lessThan\":\"8b519cbcabe836a441369fbec1a8a6518a709251\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"include/net/tc_act/tc_pedit.h\",\"net/sched/act_api.c\",\"net/sched/act_pedit.c\",\"net/sched/cls_api.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"4.11\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"4.11\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.145\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.97\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.40\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.5\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/0d8532a5e972a5351cf4ee4a435e0d65cbba8f23\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/27488e1a7f19757e6146edca9458ed4ffc545557\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/6f9b23eb92a894ae1118893996943990ee0b860e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/8b519cbcabe836a441369fbec1a8a6518a709251\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/8e49cd891bda447c68122d672510a604a8bb6b24\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-19T19:45:49+00:00",
      "cve": "CVE-2026-72338",
      "id": "CVE-2026-72338",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "245",
      "product_status:known_not_affected": "29",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: net/sched: act_pedit: fix TOCTOU heap OOB write in tc offload",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72338.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.
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Detection rules are retrieved from Rulezet.