Vulnerability-Lookup

GHSA-3CFM-HJ78-94WF

Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-17 06:33

Details

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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-72350"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T06:22:08Z",
    "severity": "HIGH"
  },
  "details": "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.",
  "id": "GHSA-3cfm-hj78-94wf",
  "modified": "2026-08-17T06:33:24Z",
  "published": "2026-08-15T06:32:21Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72350"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/00d034fe8230dfc5832fe011ff2d81c1a2cc7a29"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0a8b7a6d763775709c601f584e709ae48bcc000a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/64cdf7d30ac18e43df6c48004435febb965809a8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/728f479dc0447ae7eaef87926ff49142e415a811"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a597a722fb71a534138c20359b655726622b5f17"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b33b44250d57ab0e5a1e2571b5285fb0d0a7f382"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ca7c92d9701249e6daf132087756a88cbf2bb2a3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cce42014415cecd98aa49b3950e7b02ee7c81268"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

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

Vulnerability from cvelistv5 – Published: 2026-08-15 05:55 – Updated: 2026-08-17 05:43

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

Linux mitre root Scorecard

References

8 references

URL	Tags
https://git.kernel.org/stable/c/ca7c92d9701249e6d…
https://git.kernel.org/stable/c/b33b44250d57ab0e5…
https://git.kernel.org/stable/c/728f479dc0447ae7e…
https://git.kernel.org/stable/c/0a8b7a6d763775709…
https://git.kernel.org/stable/c/cce42014415cecd98…
https://git.kernel.org/stable/c/a597a722fb71a5341…
https://git.kernel.org/stable/c/00d034fe8230dfc58…
https://git.kernel.org/stable/c/64cdf7d30ac18e43d…

Impacted products

2 products

Vendor	Product	Version
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)
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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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/netfilter/xt_u32.c"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "lessThan": "ca7c92d9701249e6daf132087756a88cbf2bb2a3",
              "status": "affected",
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            {
              "lessThan": "728f479dc0447ae7eaef87926ff49142e415a811",
              "status": "affected",
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              "versionType": "git"
            },
            {
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              "status": "affected",
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              "versionType": "git"
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            {
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            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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            {
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              "status": "unaffected",
              "version": "5.10.261",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.212",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "6.1.178",
              "versionType": "semver"
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            {
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              "status": "unaffected",
              "version": "6.6.145",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
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              "versionType": "semver"
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            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.40",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
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                },
                {
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                },
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                  "versionStartIncluding": "2.6.23",
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                {
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                {
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                  "versionStartIncluding": "2.6.23",
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          "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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            "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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        }
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        "dateUpdated": "2026-08-17T05:43:07.758Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        {
          "url": "https://git.kernel.org/stable/c/64cdf7d30ac18e43df6c48004435febb965809a8"
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      "title": "netfilter: xt_u32: reject invalid shift counts",
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    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72350",
    "datePublished": "2026-08-15T05:55:53.532Z",
    "dateReserved": "2026-08-09T03:40:39.921Z",
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    "state": "PUBLISHED"
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}

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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GHSA-3CFM-HJ78-94WF

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

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