{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "LOCAL",
              "availabilityImpact": "HIGH",
              "baseScore": 7.1,
              "baseSeverity": "HIGH",
              "confidentialityImpact": "HIGH",
              "integrityImpact": "NONE",
              "privilegesRequired": "LOW",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2025-21789",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-10-01T19:29:57.287707Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-125",
                "description": "CWE-125 Out-of-bounds Read",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-10-01T19:36:39.729Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/loongarch/lib/csum.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "964a8895704a22efc06a2a3276b624a5ae985a06",
              "status": "affected",
              "version": "69e3a6aa6be21de6aaf38130fad97ecde34a193c",
              "versionType": "git"
            },
            {
              "lessThan": "9f15a8df542c0f08732a67d1a14ee7c22948fb97",
              "status": "affected",
              "version": "69e3a6aa6be21de6aaf38130fad97ecde34a193c",
              "versionType": "git"
            },
            {
              "lessThan": "d6508ffff32b44b6d0de06704034e4eef1c307a7",
              "status": "affected",
              "version": "69e3a6aa6be21de6aaf38130fad97ecde34a193c",
              "versionType": "git"
            },
            {
              "lessThan": "6287f1a8c16138c2ec750953e35039634018c84a",
              "status": "affected",
              "version": "69e3a6aa6be21de6aaf38130fad97ecde34a193c",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/loongarch/lib/csum.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.4"
            },
            {
              "lessThan": "6.4",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.79",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.16",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.13.*",
              "status": "unaffected",
              "version": "6.13.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.14",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.79",
                  "versionStartIncluding": "6.4",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.16",
                  "versionStartIncluding": "6.4",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.13.4",
                  "versionStartIncluding": "6.4",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.14",
                  "versionStartIncluding": "6.4",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nLoongArch: csum: Fix OoB access in IP checksum code for negative lengths\n\nCommit 69e3a6aa6be2 (\"LoongArch: Add checksum optimization for 64-bit\nsystem\") would cause an undefined shift and an out-of-bounds read.\n\nCommit 8bd795fedb84 (\"arm64: csum: Fix OoB access in IP checksum code\nfor negative lengths\") fixes the same issue on ARM64."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.3,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The negative length originates from skb metadata (csum_start vs. transport header offset) that the attacker sets locally via an AF_PACKET/tun socket with virtio_net_hdr, not from remote packet header fields \u2014 every RX path that derives lengths from peer-supplied headers validates them first (e.g. `tcf_csum_skb_nextlayer()`\u0027s `ipl \u003c hl` check). Exploitation therefore requires local socket API access.\nAC:L - The attacker deterministically chooses csum_start, csum_offset and gso_size in the virtio_net_hdr and immediately drives the packet through the GSO segmentation path; there is no race, no memory-layout dependency, and no state outside the attacker\u0027s control.\nPR:L - An unprivileged local user can obtain CAP_NET_RAW in a new user+network namespace (`unshare -Urn`) and open the AF_PACKET socket needed to inject the crafted virtio_net_hdr; no real root and no init-namespace capability is required.\nUI:N - The entire sequence is a single sendmsg() by the attacker\u0027s own process; no victim action, mount, or file open is involved.\nS:U - The out-of-bounds read stays within the kernel\u0027s own address space and security authority \u2014 there is no VM, IOMMU, or sandbox boundary crossed.\nC:H - This is a slab-out-of-bounds read (KASAN reports it as an unbounded ~4 GB read) whose out-of-bounds bytes are folded into the checksum that is then written into the outgoing packet header and transmitted, giving the attacker an observable channel onto adjacent kernel heap contents.\nI:L - The undefined shift makes the tail-masking meaningless, so a corrupted checksum is computed from out-of-bounds data and stored into the transmitted packet\u0027s checksum field; this modifies network data but yields no kernel memory write primitive.\nA:H - On KASAN/UBSAN-instrumented kernels the negative length produces a slab-out-of-bounds report and an undefined-shift splat that panics under the widely deployed panic_on_warn setting, and the huge shadow-memory scan from `kasan_check_read()` with a ~4 GB size makes an oops the expected outcome."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T11:54:27.092Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/964a8895704a22efc06a2a3276b624a5ae985a06"
        },
        {
          "url": "https://git.kernel.org/stable/c/9f15a8df542c0f08732a67d1a14ee7c22948fb97"
        },
        {
          "url": "https://git.kernel.org/stable/c/d6508ffff32b44b6d0de06704034e4eef1c307a7"
        },
        {
          "url": "https://git.kernel.org/stable/c/6287f1a8c16138c2ec750953e35039634018c84a"
        }
      ],
      "title": "LoongArch: csum: Fix OoB access in IP checksum code for negative lengths",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-21789",
    "datePublished": "2025-02-27T02:18:27.817Z",
    "dateReserved": "2024-12-29T08:45:45.766Z",
    "dateUpdated": "2026-08-05T11:54:27.092Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}