CVE-2026-97597 (GCVE-0-2026-97597)

Vulnerability from cvelistv5 – Published: 2026-09-25 10:22 – Updated: 2026-09-25 10:22
VLAI
Title
ipv6: flowlabel: cap duplicate leases per socket
Summary
In the Linux kernel, the following vulnerability has been resolved: ipv6: flowlabel: cap duplicate leases per socket ipv6_flowlabel_get() allocates an ipv6_fl_socklist entry for every successful GET. The recheck path for a compatible existing flowlabel links another lease without applying any lease admission check. Repeated GET requests for one shareable label can therefore grow a socket's lease list without bound. Reject a new unprivileged lease once the socket already holds FL_MAX_PER_SOCK leases. Check this on the shared recheck path so reuse of a globally interned label, including the fl_intern() collision path, is covered as well. New-label admission remains under the existing mem_check() policy. Use capable(CAP_NET_ADMIN) rather than ns_capable(), matching mem_check(). An unprivileged user must not bypass the cap by creating a user namespace and a netns where they have CAP_NET_ADMIN, which would still consume host memory. Check the capability only when the socket reaches the limit, so successful unprivileged GET requests below the cap do not generate a capability audit. Do the admission check before updating linger and expires so a rejected GET does not refresh the shared label, matching the existing socket-list allocation failure path.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 2f1a6dd5c80ceb902f50449efe899f29cd7918e3 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 467467bf4209f9f8add0c648bae763f92a0224c3 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 8d6cd188508513503805c156165de38e4e4a8615 (git)
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Linux Linux Affected: 2.6.12
Unaffected: 0 , < 2.6.12 (semver)
Unaffected: 6.18.53 , ≤ 6.18.* (semver)
Unaffected: 7.2.7 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc3 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
            "net/ipv6/ip6_flowlabel.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: flowlabel: cap duplicate leases per socket\n\nipv6_flowlabel_get() allocates an ipv6_fl_socklist entry for every\nsuccessful GET. The recheck path for a compatible existing flowlabel\nlinks another lease without applying any lease admission check. Repeated\nGET requests for one shareable label can therefore grow a socket\u0027s lease\nlist without bound.\n\nReject a new unprivileged lease once the socket already holds\nFL_MAX_PER_SOCK leases. Check this on the shared recheck path so reuse\nof a globally interned label, including the fl_intern() collision path,\nis covered as well. New-label admission remains under the existing\nmem_check() policy.\n\nUse capable(CAP_NET_ADMIN) rather than ns_capable(), matching\nmem_check(). An unprivileged user must not bypass the cap by creating a\nuser namespace and a netns where they have CAP_NET_ADMIN, which would\nstill consume host memory.\n\nCheck the capability only when the socket reaches the limit, so\nsuccessful unprivileged GET requests below the cap do not generate a\ncapability audit. Do the admission check before updating linger and\nexpires so a rejected GET does not refresh the shared label, matching\nthe existing socket-list allocation failure path."
        }
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        "dateUpdated": "2026-09-25T10:22:12.378Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        },
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    "datePublished": "2026-09-25T10:22:12.378Z",
    "dateReserved": "2026-09-24T16:01:01.157Z",
    "dateUpdated": "2026-09-25T10:22:12.378Z",
    "state": "PUBLISHED"
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      "date": "2026-09-28",
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      "percentile": "0.10074"
    },
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      "id": "msrc_CVE-2026-97597",
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      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "ipv6: flowlabel: cap duplicate leases per socket",
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        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: flowlabel: cap duplicate leases per socket\n\nipv6_flowlabel_get() allocates an ipv6_fl_socklist entry for every\nsuccessful GET. The recheck path for a compatible existing flowlabel\nlinks another lease without applying any lease admission check. Repeated\nGET requests for one shareable label can therefore grow a socket\u0027s lease\nlist without bound.\n\nReject a new unprivileged lease once the socket already holds\nFL_MAX_PER_SOCK leases. Check this on the shared recheck path so reuse\nof a globally interned label, including the fl_intern() collision path,\nis covered as well. New-label admission remains under the existing\nmem_check() policy.\n\nUse capable(CAP_NET_ADMIN) rather than ns_capable(), matching\nmem_check(). An unprivileged user must not bypass the cap by creating a\nuser namespace and a netns where they have CAP_NET_ADMIN, which would\nstill consume host memory.\n\nCheck the capability only when the socket reaches the limit, so\nsuccessful unprivileged GET requests below the cap do not generate a\ncapability audit. Do the admission check before updating linger and\nexpires so a rejected GET does not refresh the shared label, matching\nthe existing socket-list allocation failure path."
          }
        ],
        "id": "CVE-2026-97597",
        "lastModified": "2026-09-25T11:17:11.017",
        "metrics": {},
        "published": "2026-09-25T11:17:11.017",
        "references": [
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    }
  }
}



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