CVE-2026-98255 (GCVE-0-2026-98255)
Vulnerability from cvelistv5
Published
2026-10-06 08:45
Modified
2026-10-19 09:16
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: tcp: exclude old ACKs from tcp fast path Exclude old ACKs before SND.UNA from the tcp fast path as well as ACKs after SND.NXT. Such ACKs will fall through to the slow path, where tcp_ack() performs the appropriate validation and challenge ACK handling according to RFC5961 and Commit 3d501dd326fb1c7 ("tcp: do not accept ACK of bytes we never sent"). This prevents old ACKs from being accepted or modifying connection state as part of the fast path before appropriate ACK validation is applied. In particular, this prevents payload carried by a segment with an excessively old ACK from advancing RCV.NXT before the ACK is rejected.
References
Impacted products
Vendor Product Version
Linux Linux Version: 31770e34e43d6c8dee129bfee77e56c34e61f0e5
Version: 31770e34e43d6c8dee129bfee77e56c34e61f0e5
Version: 31770e34e43d6c8dee129bfee77e56c34e61f0e5
Version: 31770e34e43d6c8dee129bfee77e56c34e61f0e5
Version: 31770e34e43d6c8dee129bfee77e56c34e61f0e5
Version: 31770e34e43d6c8dee129bfee77e56c34e61f0e5
Version: 31770e34e43d6c8dee129bfee77e56c34e61f0e5
Version: 31770e34e43d6c8dee129bfee77e56c34e61f0e5
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/tcp_input.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "07cacab90290f795bad2e566790f4ba8e84cdf5f",
              "status": "affected",
              "version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5",
              "versionType": "git"
            },
            {
              "lessThan": "6eb9b697f50b73b9684e466c1e97f4ca8e947a59",
              "status": "affected",
              "version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5",
              "versionType": "git"
            },
            {
              "lessThan": "b86e1e5a4bbcbbccde8b7a3d3486604b581f6628",
              "status": "affected",
              "version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5",
              "versionType": "git"
            },
            {
              "lessThan": "1c8448db5cf35a13d82b0c9004ffdb49358883e7",
              "status": "affected",
              "version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5",
              "versionType": "git"
            },
            {
              "lessThan": "8309dc2cc360056aa9cd2acfbfc25930798c3b66",
              "status": "affected",
              "version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5",
              "versionType": "git"
            },
            {
              "lessThan": "ff037920c688ae6ca1153fec01e90e6782712455",
              "status": "affected",
              "version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5",
              "versionType": "git"
            },
            {
              "lessThan": "8205ac5ddb42a1843fa8d6a8c295b5c7f4f8c6ed",
              "status": "affected",
              "version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5",
              "versionType": "git"
            },
            {
              "lessThan": "f81e6c3fb06327bc49cdd6e559845293ba06a704",
              "status": "affected",
              "version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/tcp_input.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.14"
            },
            {
              "lessThan": "4.14",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.271",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.222",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.189",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.112",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.54",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.271",
                  "versionStartIncluding": "4.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.222",
                  "versionStartIncluding": "4.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.189",
                  "versionStartIncluding": "4.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.158",
                  "versionStartIncluding": "4.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.112",
                  "versionStartIncluding": "4.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.54",
                  "versionStartIncluding": "4.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.8",
                  "versionStartIncluding": "4.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "4.14",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: exclude old ACKs from tcp fast path\n\nExclude old ACKs before SND.UNA from the tcp fast path\nas well as ACKs after SND.NXT.\n\nSuch ACKs will fall through to the slow path, where tcp_ack()\nperforms the appropriate validation and challenge ACK handling\naccording to RFC5961 and Commit 3d501dd326fb1c7 (\"tcp: do not\naccept ACK of bytes we never sent\").\n\nThis prevents old ACKs from being accepted\nor modifying connection state as part of the fast path before\nappropriate ACK validation is applied.\nIn particular, this prevents payload carried by a segment with\nan excessively old ACK from advancing RCV.NXT before the ACK\nis rejected."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:16:26.522Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/07cacab90290f795bad2e566790f4ba8e84cdf5f"
        },
        {
          "url": "https://git.kernel.org/stable/c/6eb9b697f50b73b9684e466c1e97f4ca8e947a59"
        },
        {
          "url": "https://git.kernel.org/stable/c/b86e1e5a4bbcbbccde8b7a3d3486604b581f6628"
        },
        {
          "url": "https://git.kernel.org/stable/c/1c8448db5cf35a13d82b0c9004ffdb49358883e7"
        },
        {
          "url": "https://git.kernel.org/stable/c/8309dc2cc360056aa9cd2acfbfc25930798c3b66"
        },
        {
          "url": "https://git.kernel.org/stable/c/ff037920c688ae6ca1153fec01e90e6782712455"
        },
        {
          "url": "https://git.kernel.org/stable/c/8205ac5ddb42a1843fa8d6a8c295b5c7f4f8c6ed"
        },
        {
          "url": "https://git.kernel.org/stable/c/f81e6c3fb06327bc49cdd6e559845293ba06a704"
        }
      ],
      "title": "tcp: exclude old ACKs from tcp fast path",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98255",
    "datePublished": "2026-10-06T08:45:21.397Z",
    "dateReserved": "2026-09-25T10:25:14.331Z",
    "dateUpdated": "2026-10-19T09:16:26.522Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.