CVE-2026-53240 (GCVE-0-2026-53240)
Vulnerability from cvelistv5
Published
2026-06-25 08:39
Modified
2026-08-05 12:34
Severity ?
8.8 (High) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: xfrm: iptfs: fix use-after-free on first_skb in __input_process_payload __input_process_payload() stores first_skb into xtfs->ra_newskb under drop_lock when starting partial reassembly, then unlocks and breaks out of the processing loop. The post-loop check reads xtfs->ra_newskb without the lock to decide whether first_skb is still owned: if (first_skb && first_iplen && !defer && first_skb != xtfs->ra_newskb) Between spin_unlock and this read, a concurrent CPU running iptfs_reassem_cont() (or the drop_timer hrtimer) can complete reassembly, NULL xtfs->ra_newskb, and free the skb. The check then evaluates first_skb != NULL as true, and pskb_trim/ip_summed/consume_skb operate on the freed skb — a use-after-free in skbuff_head_cache. Replace the unlocked read with a local bool that records whether first_skb was handed to the reassembly state in the current call. The flag is set after the existing spin_unlock, before the break, using the pointer equality that is stable at that point (first_skb == skb iff first_skb was stored in ra_newskb).
References
Impacted products
Vendor Product Version
Linux Linux Version: 3f3339885fb343b7b42d7c34717108ce07da24ae
Version: 3f3339885fb343b7b42d7c34717108ce07da24ae
Version: 3f3339885fb343b7b42d7c34717108ce07da24ae
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/xfrm/xfrm_iptfs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "8d9a79fbf5172d9c4c0146057af2360913265a11",
              "status": "affected",
              "version": "3f3339885fb343b7b42d7c34717108ce07da24ae",
              "versionType": "git"
            },
            {
              "lessThan": "ff2ee35b6ce5fa8a8e24ea50b15733d5c8780198",
              "status": "affected",
              "version": "3f3339885fb343b7b42d7c34717108ce07da24ae",
              "versionType": "git"
            },
            {
              "lessThan": "eb48730bb827d1550401a5d391903f9d90b493c8",
              "status": "affected",
              "version": "3f3339885fb343b7b42d7c34717108ce07da24ae",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/xfrm/xfrm_iptfs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.14"
            },
            {
              "lessThan": "6.14",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.36",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.13",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.36",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0.13",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: iptfs: fix use-after-free on first_skb in __input_process_payload\n\n__input_process_payload() stores first_skb into xtfs-\u003era_newskb under\ndrop_lock when starting partial reassembly, then unlocks and breaks out\nof the processing loop. The post-loop check reads xtfs-\u003era_newskb\nwithout the lock to decide whether first_skb is still owned:\n\n    if (first_skb \u0026\u0026 first_iplen \u0026\u0026 !defer \u0026\u0026 first_skb != xtfs-\u003era_newskb)\n\nBetween spin_unlock and this read, a concurrent CPU running\niptfs_reassem_cont() (or the drop_timer hrtimer) can complete\nreassembly, NULL xtfs-\u003era_newskb, and free the skb. The check then\nevaluates first_skb != NULL as true, and pskb_trim/ip_summed/consume_skb\noperate on the freed skb \u2014 a use-after-free in skbuff_head_cache.\n\nReplace the unlocked read with a local bool that records whether\nfirst_skb was handed to the reassembly state in the current call. The\nflag is set after the existing spin_unlock, before the break, using the\npointer equality that is stable at that point (first_skb == skb iff\nfirst_skb was stored in ra_newskb)."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The vulnerable IPTFS parser is reached from the network receive path through xfrm4/xfrm6 ESP handling, xfrm_input, and iptfs_input on an inbound IPTFS SA. A reasonable high-impact deployment is an internet-reachable IPsec/IPTFS gateway processing remote peer traffic.\nAC:L - The bug is a use-after-free race after first_skb is handed to reassembly, and the attacker can drive the needed fragmented/reordered IPTFS packets and concurrent continuation processing. There is no condition beyond the attacker\u2019s control once valid IPTFS ESP traffic reaches the SA.\nPR:L - Unauthenticated packets are rejected by XFRM/ESP state lookup, replay, and crypto verification before IPTFS parsing, so a remote attacker needs valid SA access or credentials. Locally, creating the IPTFS SA requires CAP_NET_ADMIN in a network namespace, which is reachable as low privilege via user namespaces.\nUI:N - No victim user action is required after the vulnerable SA is present; packet receipt alone triggers the path. The attacker sends crafted traffic to the configured endpoint.\nS:U - The impact is kernel memory corruption within the same host kernel security authority. This is not a VM escape, IOMMU bypass, or other cross-scope boundary.\nC:H - This is a use-after-free of an sk_buff from skbuff_head_cache, and freed object reuse can expose kernel memory or support stronger disclosure primitives. Under the required guidance, UAF memory corruption warrants high confidentiality impact.\nI:H - The stale sk_buff is subsequently used by pskb_trim, field writes, and freeing paths, giving a plausible route to heap corruption and control-flow or data corruption. Under the required guidance, UAF memory corruption warrants high integrity impact.\nA:H - The stale sk_buff access can corrupt kernel heap state or crash in packet processing/freeing paths. A kernel oops, panic, or repeatable crash is high availability impact."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:34:26.772Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/8d9a79fbf5172d9c4c0146057af2360913265a11"
        },
        {
          "url": "https://git.kernel.org/stable/c/ff2ee35b6ce5fa8a8e24ea50b15733d5c8780198"
        },
        {
          "url": "https://git.kernel.org/stable/c/eb48730bb827d1550401a5d391903f9d90b493c8"
        }
      ],
      "title": "xfrm: iptfs: fix use-after-free on first_skb in __input_process_payload",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-53240",
    "datePublished": "2026-06-25T08:39:35.809Z",
    "dateReserved": "2026-06-09T07:44:35.393Z",
    "dateUpdated": "2026-08-05T12:34:26.772Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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