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CVE-2026-72350 (GCVE-0-2026-72350)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:55 – Updated: 2026-08-17 05:43
VLAI
Title
netfilter: xt_u32: reject invalid shift counts
Summary
In the Linux kernel, the following vulnerability has been resolved: netfilter: xt_u32: reject invalid shift counts u32_match_it() executes rule-supplied shift operands on a 32-bit value. A malformed u32 rule can provide a shift count of 32 or more, triggering an undefined shift out-of-bounds during packet evaluation. Validate XT_U32_LEFTSH and XT_U32_RIGHTSH operands in u32_mt_checkentry() and reject malformed rules before they reach the packet path.
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: 1b50b8a371e90a5e110f466e4ac02cf6b5f681de , < ca7c92d9701249e6daf132087756a88cbf2bb2a3 (git)
Affected: 1b50b8a371e90a5e110f466e4ac02cf6b5f681de , < b33b44250d57ab0e5a1e2571b5285fb0d0a7f382 (git)
Affected: 1b50b8a371e90a5e110f466e4ac02cf6b5f681de , < 728f479dc0447ae7eaef87926ff49142e415a811 (git)
Affected: 1b50b8a371e90a5e110f466e4ac02cf6b5f681de , < 0a8b7a6d763775709c601f584e709ae48bcc000a (git)
Affected: 1b50b8a371e90a5e110f466e4ac02cf6b5f681de , < cce42014415cecd98aa49b3950e7b02ee7c81268 (git)
Affected: 1b50b8a371e90a5e110f466e4ac02cf6b5f681de , < a597a722fb71a534138c20359b655726622b5f17 (git)
Affected: 1b50b8a371e90a5e110f466e4ac02cf6b5f681de , < 00d034fe8230dfc5832fe011ff2d81c1a2cc7a29 (git)
Affected: 1b50b8a371e90a5e110f466e4ac02cf6b5f681de , < 64cdf7d30ac18e43df6c48004435febb965809a8 (git)
guessed Create a notification for this product.
Linux Linux Affected: 2.6.23
Unaffected: 0 , < 2.6.23 (semver)
Unaffected: 5.10.261 , ≤ 5.10.* (semver)
Unaffected: 5.15.212 , ≤ 5.15.* (semver)
Unaffected: 6.1.178 , ≤ 6.1.* (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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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: xt_u32: reject invalid shift counts\n\nu32_match_it() executes rule-supplied shift operands on a 32-bit\nvalue. A malformed u32 rule can provide a shift count of 32 or more,\ntriggering an undefined shift out-of-bounds during packet evaluation.\n\nValidate XT_U32_LEFTSH and XT_U32_RIGHTSH operands in\nu32_mt_checkentry() and reject malformed rules before they reach the\npacket path."
        }
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
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              "value": "AV:L - Malicious xt_u32 match rules are installed via IPT_SO_SET_REPLACE setsockopt or nftables NFNetlink (nft_compat match); per kernel CNA guidance netfilter/xtables rule setup is Local even though installed rules evaluate on ingress/egress packets through ipt_do_table.\nAC:L - The attacker fully controls XT_U32_LEFTSH/RIGHTSH shift operands (\u003e=32) in matchinfo and can send triggering packets through the hooked netfilter chain; no race or uncontrollable victim state is required.\nPR:L - Installing xt_u32 iptables/nftables rules requires CAP_NET_ADMIN, obtainable by unprivileged users in user/network namespaces via unshare -Urn; ip_tables.c and nfnetlink enforce ns_capable/netlink_net_capable against the namespace user_ns.\nUI:N - The attacker installs the malicious u32 match rule and generates matching traffic in their namespace; no separate victim action (opening files, mounting media, clicking links) is needed.\nS:U - Undefined shift during xt_u32 packet matching and any resulting kernel crash remain within the host kernel security authority; this is standard local kernel compromise, not a VM escape or sandbox boundary crossing.\nC:H - Undefined-behavior shifts on packet-derived u32 values corrupt val and @ offset accumulation, driving attacker-influenced skb_copy_bits reads at unintended offsets; per CNA guidance exploitable kernel memory-unsafe arithmetic warrants High confidentiality.\nI:H - Invalid shift counts corrupt val/at control flow in the u32_match_it hot path; C11 undefined behavior in kernel netfilter matching is exploitable for integrity compromise and potential code execution per CNA memory-corruption guidance.\nA:H - Evaluating a malformed xt_u32 rule with shift\u003e=32 triggers undefined shift-out-of-bounds during packet matching; vulnerable kernels also BUG() on skb_copy_bits failure, provoking kernel panic/oops during rule evaluation."
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        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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    "datePublished": "2026-08-15T05:55:53.532Z",
    "dateReserved": "2026-08-09T03:40:39.921Z",
    "dateUpdated": "2026-08-17T05:43:07.758Z",
    "state": "PUBLISHED"
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A malformed u32 rule can provide a shift count of 32 or more,\\ntriggering an undefined shift out-of-bounds during packet evaluation.\\n\\nValidate XT_U32_LEFTSH and XT_U32_RIGHTSH operands in\\nu32_mt_checkentry() and reject malformed rules before they reach the\\npacket path.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"net/netfilter/xt_u32.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"1b50b8a371e90a5e110f466e4ac02cf6b5f681de\",\"lessThan\":\"ca7c92d9701249e6daf132087756a88cbf2bb2a3\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1b50b8a371e90a5e110f466e4ac02cf6b5f681de\",\"lessThan\":\"b33b44250d57ab0e5a1e2571b5285fb0d0a7f382\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1b50b8a371e90a5e110f466e4ac02cf6b5f681de\",\"lessThan\":\"728f479dc0447ae7eaef87926ff49142e415a811\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1b50b8a371e90a5e110f466e4ac02cf6b5f681de\",\"lessThan\":\"0a8b7a6d763775709c601f584e709ae48bcc000a\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1b50b8a371e90a5e110f466e4ac02cf6b5f681de\",\"lessThan\":\"cce42014415cecd98aa49b3950e7b02ee7c81268\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1b50b8a371e90a5e110f466e4ac02cf6b5f681de\",\"lessThan\":\"a597a722fb71a534138c20359b655726622b5f17\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1b50b8a371e90a5e110f466e4ac02cf6b5f681de\",\"lessThan\":\"00d034fe8230dfc5832fe011ff2d81c1a2cc7a29\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"1b50b8a371e90a5e110f466e4ac02cf6b5f681de\",\"lessThan\":\"64cdf7d30ac18e43df6c48004435febb965809a8\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"net/netfilter/xt_u32.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"2.6.23\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"2.6.23\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.10.261\",\"lessThanOrEqual\":\"5.10.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.212\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.178\",\"lessThanOrEqual\":\"6.1.*\",\"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/00d034fe8230dfc5832fe011ff2d81c1a2cc7a29\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/0a8b7a6d763775709c601f584e709ae48bcc000a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/64cdf7d30ac18e43df6c48004435febb965809a8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/728f479dc0447ae7eaef87926ff49142e415a811\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/a597a722fb71a534138c20359b655726622b5f17\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b33b44250d57ab0e5a1e2571b5285fb0d0a7f382\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ca7c92d9701249e6daf132087756a88cbf2bb2a3\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/cce42014415cecd98aa49b3950e7b02ee7c81268\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Low",
      "current_release_date": "2026-08-19T17:16:17+00:00",
      "cve": "CVE-2026-72350",
      "id": "CVE-2026-72350",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "166",
      "product_status:known_not_affected": "108",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: netfilter: xt_u32: reject invalid shift counts",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72350.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

Author Source Type Date Other

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.