CVE-2026-72348 (GCVE-0-2026-72348)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:55 – Updated: 2026-08-17 05:43
VLAI
Title
netfilter: ip6tables: mark malformed IPv6 extension headers for hotdrop
Summary
In the Linux kernel, the following vulnerability has been resolved: netfilter: ip6tables: mark malformed IPv6 extension headers for hotdrop The ah, hbh and rt matches check that the fixed extension header is present, then use the header length field to derive the advertised extension header length for matching. For the ah match, add the missing advertised-length check. For hbh and rt, update the existing advertised-length checks. In all three cases, set hotdrop to true before returning false when the advertised extension header length exceeds the available skb data. Returning false treats the packet as a rule mismatch. Set hotdrop to true and drop malformed packets so they cannot bypass rules intended to drop packets with these IPv6 extension headers.
Severity
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < f16d856b6af5fd0e7cb0b0212f70825b599ef72e (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < fc416870100cf16d5b9495199355a679c3a02d48 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < f775fcf384b06f35b612f78fa5601fee99eb6513 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 2fd89a50a9783eed8ed23866b11c8b3d8779a7a8 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 3578b6d92a5b1e603ae6e8c8f5538a709f03aba4 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 3d441be2b1c5e98167302fa1c7b61960a067b112 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < d5e39e5eb6b30bc4a3bb7aba54c293cf36a806c7 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 43ccc20b5a733226417832cf16ef45322e594990 (git)
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Linux Linux Affected: 2.6.12
Unaffected: 0 , < 2.6.12 (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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{
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ip6tables: mark malformed IPv6 extension headers for hotdrop\n\nThe ah, hbh and rt matches check that the fixed extension header is\npresent, then use the header length field to derive the advertised\nextension header length for matching.\n\nFor the ah match, add the missing advertised-length check. For hbh\nand rt, update the existing advertised-length checks. In all three\ncases, set hotdrop to true before returning false when the advertised\nextension header length exceeds the available skb data.\n\nReturning false treats the packet as a rule mismatch. Set hotdrop to\ntrue and drop malformed packets so they cannot bypass rules intended\nto drop packets with these IPv6 extension headers."
        }
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              "value": "AV:N - Malformed IPv6 packets reach ah/hbh/rt ip6tables match functions through netfilter PREROUTING, INPUT, and FORWARD hooks on internet-facing servers, routers, and gateways without any local access.\nAC:L - An attacker reliably crafts IPv6 packets with AH, HBH, or routing extension headers whose length field exceeds available skb data; no race, timing window, or uncontrollable victim state is required.\nPR:N - Exploitation requires only sending IPv6 traffic to a host with ip6tables rules using the ah, hbh, or rt matches; no authentication, local access, or CAP_NET_ADMIN is needed by the attacker.\nUI:N - No victim interaction is required; exploitation is achieved solely by sending crafted network packets to a system running vulnerable ip6tables extension-header match rules.\nS:U - Impact is confined to bypassing kernel netfilter policy enforcement on the affected host or gateway; it does not cross VM, container, or IOMMU security boundaries.\nC:H - Bypassing DROP rules intended to block AH, HBH, or routing-header traffic can admit packets to previously firewalled services and confidential data on protected internal networks.\nI:H - Malformed packets are treated as rule non-matches instead of hotdrop failures, allowing traffic administrators configured ip6tables to reject, bypassing enforced network access controls.\nA:N - The flaw is a logic error in match handling that neither corrupts memory nor triggers kernel oops, panic, or hang; there is no direct availability impact from the bug itself."
            }
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        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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    "dateReserved": "2026-08-09T03:40:39.921Z",
    "dateUpdated": "2026-08-17T05:43:06.635Z",
    "state": "PUBLISHED"
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  }
}



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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.