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EUVD-2026-344408

European Vulnerability Database identifier assigned by ENISA

Reserved

2026-10-02 07:56

Assigner

ENISA

Alias of

a CVE record, shown under related vulnerabilities. This identifier carries no description, severity or references of its own: they belong to that CVE.

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{
  "assigner": "ENISA",
  "date_reserved": "2026-10-02T07:56:09.489871+00:00",
  "id": "EUVD-2026-344408"
}

CVE-2021-47162 (GCVE-0-2021-47162)

Vulnerability from cvelistv5 – Published: 2024-03-25 09:16 – Updated: 2026-08-05 08:46

Title

tipc: skb_linearize the head skb when reassembling msgs

Summary

In the Linux kernel, the following vulnerability has been resolved: tipc: skb_linearize the head skb when reassembling msgs It's not a good idea to append the frag skb to a skb's frag_list if the frag_list already has skbs from elsewhere, such as this skb was created by pskb_copy() where the frag_list was cloned (all the skbs in it were skb_get'ed) and shared by multiple skbs. However, the new appended frag skb should have been only seen by the current skb. Otherwise, it will cause use after free crashes as this appended frag skb are seen by multiple skbs but it only got skb_get called once. The same thing happens with a skb updated by pskb_may_pull() with a skb_cloned skb. Li Shuang has reported quite a few crashes caused by this when doing testing over macvlan devices: [] kernel BUG at net/core/skbuff.c:1970! [] Call Trace: [] skb_clone+0x4d/0xb0 [] macvlan_broadcast+0xd8/0x160 [macvlan] [] macvlan_process_broadcast+0x148/0x150 [macvlan] [] process_one_work+0x1a7/0x360 [] worker_thread+0x30/0x390 [] kernel BUG at mm/usercopy.c:102! [] Call Trace: [] __check_heap_object+0xd3/0x100 [] __check_object_size+0xff/0x16b [] simple_copy_to_iter+0x1c/0x30 [] __skb_datagram_iter+0x7d/0x310 [] __skb_datagram_iter+0x2a5/0x310 [] skb_copy_datagram_iter+0x3b/0x90 [] tipc_recvmsg+0x14a/0x3a0 [tipc] [] ____sys_recvmsg+0x91/0x150 [] ___sys_recvmsg+0x7b/0xc0 [] kernel BUG at mm/slub.c:305! [] Call Trace: [] <IRQ> [] kmem_cache_free+0x3ff/0x400 [] __netif_receive_skb_core+0x12c/0xc40 [] ? kmem_cache_alloc+0x12e/0x270 [] netif_receive_skb_internal+0x3d/0xb0 [] ? get_rx_page_info+0x8e/0xa0 [be2net] [] be_poll+0x6ef/0xd00 [be2net] [] ? irq_exit+0x4f/0x100 [] net_rx_action+0x149/0x3b0 ... This patch is to fix it by linearizing the head skb if it has frag_list set in tipc_buf_append(). Note that we choose to do this before calling skb_unshare(), as __skb_linearize() will avoid skb_copy(). Also, we can not just drop the frag_list either as the early time.

Severity

9.8 (Critical)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2024-06-26 20:36 UTC

Assigner

Linux mitre root Scorecard

References

8 references

URL	Tags
https://git.kernel.org/stable/c/b2c8d28c34b307040…
https://git.kernel.org/stable/c/5489f30bb78ff0daf…
https://git.kernel.org/stable/c/436d650d374329a59…
https://git.kernel.org/stable/c/4b1761898861117c9…
https://git.kernel.org/stable/c/64d17ec9f1ded042c…
https://git.kernel.org/stable/c/6da24cfc83ba4f97e…
https://git.kernel.org/stable/c/ace300eecbccaa698…
https://git.kernel.org/stable/c/b7df21cf1b79ab702…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 45c8b7b175ceb2d542e0fe15247377bf3bce29ec , < b2c8d28c34b3070407cb1741f9ba3f15d0284b8b (git) Affected: 45c8b7b175ceb2d542e0fe15247377bf3bce29ec , < 5489f30bb78ff0dafb4229a69632afc2ba20765c (git) Affected: 45c8b7b175ceb2d542e0fe15247377bf3bce29ec , < 436d650d374329a591c30339a91fa5078052ed1e (git) Affected: 45c8b7b175ceb2d542e0fe15247377bf3bce29ec , < 4b1761898861117c97066aea6c58f68a7787f0bf (git) Affected: 45c8b7b175ceb2d542e0fe15247377bf3bce29ec , < 64d17ec9f1ded042c4b188d15734f33486ed9966 (git) Affected: 45c8b7b175ceb2d542e0fe15247377bf3bce29ec , < 6da24cfc83ba4f97ea44fc7ae9999a006101755c (git) Affected: 45c8b7b175ceb2d542e0fe15247377bf3bce29ec , < ace300eecbccaa698e2b472843c74a5f33f7dce8 (git) Affected: 45c8b7b175ceb2d542e0fe15247377bf3bce29ec , < b7df21cf1b79ab7026f545e7bf837bd5750ac026 (git) Affected: d45ed6c1ff20d3640a31f03816ca2d48fb7d6f22 (git) Affected: c19282fd54a19e4651a4e67836cd842082546677 (git) Affected: 4.1.14 , < 4.2 (semver) Affected: 4.2.7 , < 4.3 (semver)
Linux	Linux	Affected: 4.3 Unaffected: 0 , < 4.3 (semver) Unaffected: 4.4.271 , ≤ 4.4.* (semver) Unaffected: 4.9.271 , ≤ 4.9.* (semver) Unaffected: 4.14.235 , ≤ 4.14.* (semver) Unaffected: 4.19.193 , ≤ 4.19.* (semver) Unaffected: 5.4.124 , ≤ 5.4.* (semver) Unaffected: 5.10.42 , ≤ 5.10.* (semver) Unaffected: 5.12.9 , ≤ 5.12.* (semver) Unaffected: 5.13 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: skb_linearize the head skb when reassembling msgs\n\nIt\u0027s not a good idea to append the frag skb to a skb\u0027s frag_list if\nthe frag_list already has skbs from elsewhere, such as this skb was\ncreated by pskb_copy() where the frag_list was cloned (all the skbs\nin it were skb_get\u0027ed) and shared by multiple skbs.\n\nHowever, the new appended frag skb should have been only seen by the\ncurrent skb. Otherwise, it will cause use after free crashes as this\nappended frag skb are seen by multiple skbs but it only got skb_get\ncalled once.\n\nThe same thing happens with a skb updated by pskb_may_pull() with a\nskb_cloned skb. Li Shuang has reported quite a few crashes caused\nby this when doing testing over macvlan devices:\n\n  [] kernel BUG at net/core/skbuff.c:1970!\n  [] Call Trace:\n  []  skb_clone+0x4d/0xb0\n  []  macvlan_broadcast+0xd8/0x160 [macvlan]\n  []  macvlan_process_broadcast+0x148/0x150 [macvlan]\n  []  process_one_work+0x1a7/0x360\n  []  worker_thread+0x30/0x390\n\n  [] kernel BUG at mm/usercopy.c:102!\n  [] Call Trace:\n  []  __check_heap_object+0xd3/0x100\n  []  __check_object_size+0xff/0x16b\n  []  simple_copy_to_iter+0x1c/0x30\n  []  __skb_datagram_iter+0x7d/0x310\n  []  __skb_datagram_iter+0x2a5/0x310\n  []  skb_copy_datagram_iter+0x3b/0x90\n  []  tipc_recvmsg+0x14a/0x3a0 [tipc]\n  []  ____sys_recvmsg+0x91/0x150\n  []  ___sys_recvmsg+0x7b/0xc0\n\n  [] kernel BUG at mm/slub.c:305!\n  [] Call Trace:\n  []  \u003cIRQ\u003e\n  []  kmem_cache_free+0x3ff/0x400\n  []  __netif_receive_skb_core+0x12c/0xc40\n  []  ? kmem_cache_alloc+0x12e/0x270\n  []  netif_receive_skb_internal+0x3d/0xb0\n  []  ? get_rx_page_info+0x8e/0xa0 [be2net]\n  []  be_poll+0x6ef/0xd00 [be2net]\n  []  ? irq_exit+0x4f/0x100\n  []  net_rx_action+0x149/0x3b0\n\n  ...\n\nThis patch is to fix it by linearizing the head skb if it has frag_list\nset in tipc_buf_append(). Note that we choose to do this before calling\nskb_unshare(), as __skb_linearize() will avoid skb_copy(). Also, we can\nnot just drop the frag_list either as the early time."
        }
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      "metrics": [
        {
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            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The vulnerable tipc_buf_append() reassembly path is reached from tipc_udp_recv() \u2192 tipc_rcv() \u2192 tipc_link_rcv() \u2192 tipc_link_input() when processing MSG_FRAGMENTER packets over a configured TIPC UDP bearer, which is IP-routable and network-facing.\nAC:L - An attacker who can reach the UDP bearer fully controls discovery/link setup (default net_id 4711, optional crypto) and can reliably send the fragmented messages that drive reassembly; this is a deterministic shared-frag_list UAF, not a race beyond attacker control.\nPR:N - No privileges on the target are required; TIPC discovery and link establishment are unauthenticated by default, so a remote network peer can reach the reassembly code without local credentials.\nUI:N - Exploitation requires only attacker-sent TIPC packets; no victim user action such as mounting a filesystem or opening a file is needed.\nS:U - The UAF corrupts kernel memory and can elevate privilege within the same host kernel security authority; it does not cross a VM, IOMMU, or other security boundary.\nC:H - Use-after-free on sk_buff frag_list structures gives the attacker control over freed object contents and is therefore treatable as an arbitrary kernel read primitive.\nI:H - The same UAF enables heap reuse and write/control-flow hijacking primitives against kernel sk_buff state, supporting integrity compromise and code execution.\nA:H - The bug has been observed to trigger kernel BUG/oops paths (skb_clone, usercopy, slub), so availability impact includes reliable kernel crash."
            }
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        }
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        "dateUpdated": "2026-08-05T08:46:26.121Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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        },
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        },
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        },
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        },
        {
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        },
        {
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        },
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          "url": "https://git.kernel.org/stable/c/ace300eecbccaa698e2b472843c74a5f33f7dce8"
        },
        {
          "url": "https://git.kernel.org/stable/c/b7df21cf1b79ab7026f545e7bf837bd5750ac026"
        }
      ],
      "title": "tipc: skb_linearize the head skb when reassembling msgs",
      "x_generator": {
        "engine": "bippy-1.2.0"
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    }
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2021-47162",
    "datePublished": "2024-03-25T09:16:15.857Z",
    "dateReserved": "2024-03-25T09:12:14.109Z",
    "dateUpdated": "2026-08-05T08:46:26.121Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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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Action not permitted

EUVD-2026-344408

CVE-2021-47162 (GCVE-0-2021-47162)

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Sightings

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Related by attack behaviour