CVE-2026-98794

Status: ReceivedUnscored—

Severity—Unscored

Exploitation probability0.20 %higher than 9% of CVEs

Active exploitationNonot in the CISA catalog

Public exploitNot knownno public code found

In the Linux kernel, the following vulnerability has been resolved:

ipvs: filter some flags received in the backup server

While the IPVS SYNC protocol is not secure by design we can still protect the backup server from messages that can wreak havoc.

This commit addresses problems from received connection flags or their combinations. We now drop messages as follows:

1. the NO_CPORT+TEMPLATE combination allows lookups for normal connections to hit template which can break in many ways. While the master does not sync connections with NO_CPORT flag, i.e. before they are established, we still accept NO_CPORT without TEMPLATE.

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2. ONE_PACKET: it is not sent by master, so we do not expect it in backup. Before now it was ignored by IP_VS_CONN_F_BACKUP_MASK for protocol v1 while protocol v0 created connections that are not hashed and dropped immediately. Better to apply the IP_VS_CONN_F_BACKUP_MASK also to the flags from v0 messages for consistency with v1.

CVSS

NVD hasn't assigned a CVSS score to this CVE (common since the April 2026 policy change).

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.20 %
Percentile among all scored CVEs: 9
Score date: 10/20/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (1)

⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.

Linux — Linux Kernel^AI

References

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Raw JSON (NVD)

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{
  "id": "CVE-2026-98794",
  "cveTags": [],
  "metrics": {},
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "87375ab47cd0ba04124c6d3fd80db5c368f5dcb6",
              "lessThan": "f4cd1db7d421e82945713a36084bb0c35b75b27e",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "87375ab47cd0ba04124c6d3fd80db5c368f5dcb6",
              "lessThan": "55d033324f67a15ff56be6d38d6e87f644e0ed62",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "87375ab47cd0ba04124c6d3fd80db5c368f5dcb6",
              "lessThan": "45a93111835ccfea7d969ec73588e33745fd9834",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "87375ab47cd0ba04124c6d3fd80db5c368f5dcb6",
              "lessThan": "f96e91748f6304668fe647e686d199d7207d36f1",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "net/netfilter/ipvs/ip_vs_sync.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.14"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "2.6.14",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.12.113",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.56",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.2.10",
              "versionType": "semver",
              "lessThanOrEqual": "7.2.*"
            },
            {
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "net/netfilter/ipvs/ip_vs_sync.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-10-18T16:17:33.390",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/45a93111835ccfea7d969ec73588e33745fd9834",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/55d033324f67a15ff56be6d38d6e87f644e0ed62",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/f4cd1db7d421e82945713a36084bb0c35b75b27e",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/f96e91748f6304668fe647e686d199d7207d36f1",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipvs: filter some flags received in the backup server\n\nWhile the IPVS SYNC protocol is not secure by design\nwe can still protect the backup server from messages that\ncan wreak havoc.\n\nThis commit addresses problems from received connection flags\nor their combinations. We now drop messages as follows:\n\n1. the NO_CPORT+TEMPLATE combination allows lookups for normal\nconnections to hit template which can break in many ways.\nWhile the master does not sync connections with NO_CPORT flag,\ni.e. before they are established, we still accept NO_CPORT\nwithout TEMPLATE.\n\n2. ONE_PACKET: it is not sent by master, so we do not\nexpect it in backup. Before now it was ignored by\nIP_VS_CONN_F_BACKUP_MASK for protocol v1 while protocol\nv0 created connections that are not hashed and dropped\nimmediately. Better to apply the IP_VS_CONN_F_BACKUP_MASK\nalso to the flags from v0 messages for consistency with v1."
    }
  ],
  "lastModified": "2026-10-19T10:19:43.427",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}