GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

CVE-2026-43384 (GCVE-0-2026-43384)

Vulnerability from cvelistv5 – Published: 2026-05-08 14:21 – Updated: 2026-08-05 12:27
VLAI
Title
net/tcp-ao: Fix MAC comparison to be constant-time
Summary
In the Linux kernel, the following vulnerability has been resolved: net/tcp-ao: Fix MAC comparison to be constant-time To prevent timing attacks, MACs need to be compared in constant time. Use the appropriate helper function for this.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 0a3a809089eb1d4a0a2fd0c16b520d603988c859 , < 8be6ed64966da48b6c4726918f106c18742a5125 (git)
Affected: 0a3a809089eb1d4a0a2fd0c16b520d603988c859 , < a269cbdc442f8658bca35383e34b9d0b0ff95a1c (git)
Affected: 0a3a809089eb1d4a0a2fd0c16b520d603988c859 , < 080b0e210088296dd50d6637c06c1db14246adfe (git)
Affected: 0a3a809089eb1d4a0a2fd0c16b520d603988c859 , < 67edfec516d30d3e62925c397be4a1e5185802fc (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.7
Unaffected: 0 , < 6.7 (semver)
Unaffected: 6.12.78 , ≤ 6.12.* (semver)
Unaffected: 6.18.19 , ≤ 6.18.* (semver)
Unaffected: 6.19.9 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/Kconfig",
            "net/ipv4/tcp_ao.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "8be6ed64966da48b6c4726918f106c18742a5125",
              "status": "affected",
              "version": "0a3a809089eb1d4a0a2fd0c16b520d603988c859",
              "versionType": "git"
            },
            {
              "lessThan": "a269cbdc442f8658bca35383e34b9d0b0ff95a1c",
              "status": "affected",
              "version": "0a3a809089eb1d4a0a2fd0c16b520d603988c859",
              "versionType": "git"
            },
            {
              "lessThan": "080b0e210088296dd50d6637c06c1db14246adfe",
              "status": "affected",
              "version": "0a3a809089eb1d4a0a2fd0c16b520d603988c859",
              "versionType": "git"
            },
            {
              "lessThan": "67edfec516d30d3e62925c397be4a1e5185802fc",
              "status": "affected",
              "version": "0a3a809089eb1d4a0a2fd0c16b520d603988c859",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/Kconfig",
            "net/ipv4/tcp_ao.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.7"
            },
            {
              "lessThan": "6.7",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.78",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.19",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.78",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.19",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.9",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/tcp-ao: Fix MAC comparison to be constant-time\n\nTo prevent timing attacks, MACs need to be compared in constant\ntime.  Use the appropriate helper function for this."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "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 comparison is reached by inbound IPv4/IPv6 TCP packets carrying a TCP-AO option, before normal TCP processing of the segment.\nAC:L - The attacker controls the candidate MAC bytes and can send repeated chosen packets to average timing differences; no race or condition outside the attacker\u2019s control is required once a TCP-AO-protected socket is reachable.\nPR:N - The vulnerable path is the TCP-AO authentication check itself, so the attacker does not need the AO key or any local privilege before sending probes.\nUI:N - No victim user action is required; packet receipt by the configured TCP-AO endpoint is sufficient.\nS:U - The impact remains within the kernel/network endpoint and the TCP sessions protected by that endpoint, with no VM, sandbox, or separate security-authority escape.\nC:H - A successful MAC-forgery timing attack can let an unauthenticated network attacker impersonate a trusted TCP-AO peer and receive data made available to that authenticated peer.\nI:H - Forged valid TCP-AO segments can inject or alter arbitrary TCP stream/control data for protected connections, defeating the integrity guarantee TCP-AO is meant to provide.\nA:H - Forged valid TCP-AO control segments such as RST/FIN or malicious stream data can tear down or disrupt protected long-lived sessions such as routing/control-plane connections."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:27:42.918Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/8be6ed64966da48b6c4726918f106c18742a5125"
        },
        {
          "url": "https://git.kernel.org/stable/c/a269cbdc442f8658bca35383e34b9d0b0ff95a1c"
        },
        {
          "url": "https://git.kernel.org/stable/c/080b0e210088296dd50d6637c06c1db14246adfe"
        },
        {
          "url": "https://git.kernel.org/stable/c/67edfec516d30d3e62925c397be4a1e5185802fc"
        }
      ],
      "title": "net/tcp-ao: Fix MAC comparison to be constant-time",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43384",
    "datePublished": "2026-05-08T14:21:31.355Z",
    "dateReserved": "2026-05-01T14:12:56.006Z",
    "dateUpdated": "2026-08-05T12:27:42.918Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-43384",
      "date": "2026-09-16",
      "epss": "0.00457",
      "percentile": "0.38736"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-43384\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-05-08T15:16:49.720\",\"lastModified\":\"2026-06-17T10:49:29.873\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nnet/tcp-ao: Fix MAC comparison to be constant-time\\n\\nTo prevent timing attacks, MACs need to be compared in constant\\ntime.  Use the appropriate helper function for this.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"net/ipv4/Kconfig\",\"net/ipv4/tcp_ao.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"0a3a809089eb1d4a0a2fd0c16b520d603988c859\",\"lessThan\":\"8be6ed64966da48b6c4726918f106c18742a5125\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"0a3a809089eb1d4a0a2fd0c16b520d603988c859\",\"lessThan\":\"a269cbdc442f8658bca35383e34b9d0b0ff95a1c\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"0a3a809089eb1d4a0a2fd0c16b520d603988c859\",\"lessThan\":\"080b0e210088296dd50d6637c06c1db14246adfe\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"0a3a809089eb1d4a0a2fd0c16b520d603988c859\",\"lessThan\":\"67edfec516d30d3e62925c397be4a1e5185802fc\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"net/ipv4/Kconfig\",\"net/ipv4/tcp_ao.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.7\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.7\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.78\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.19\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.19.9\",\"lessThanOrEqual\":\"6.19.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.0\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":9.8,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":5.9}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"NVD-CWE-noinfo\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.7\",\"versionEndExcluding\":\"6.12.78\",\"matchCriteriaId\":\"28D591F5-B196-4CC9-905C-DC80F116E7A8\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.13\",\"versionEndExcluding\":\"6.18.19\",\"matchCriteriaId\":\"D394AC60-6F28-435F-872A-CCDF384B8331\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.19\",\"versionEndExcluding\":\"6.19.9\",\"matchCriteriaId\":\"E825E7C3-FEAC-4FD3-8A81-78D7387948C9\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*\",\"matchCriteriaId\":\"F253B622-8837-4245-BCE5-A7BF8FC76A16\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*\",\"matchCriteriaId\":\"4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/080b0e210088296dd50d6637c06c1db14246adfe\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/67edfec516d30d3e62925c397be4a1e5185802fc\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/8be6ed64966da48b6c4726918f106c18742a5125\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/a269cbdc442f8658bca35383e34b9d0b0ff95a1c\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}",
    "redhat_vex": {
      "aggregate_severity": "None",
      "current_release_date": "2026-06-28T11:40:02+00:00",
      "cve": "CVE-2026-43384",
      "id": "CVE-2026-43384",
      "initial_release_date": "2026-05-08T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: net/tcp-ao: Fix MAC comparison to be constant-time",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43384.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-11T01:18:03Z",
      "cve": "CVE-2026-43384",
      "id": "CVE-2026-43384",
      "initial_release_date": "2026-05-13T03:34:36Z",
      "product_status:first_fixed": "2",
      "product_status:known_not_affected": "370",
      "product_status:recommended": "172",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-43384",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-43384.json",
      "version": "7"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.


Detection rules are retrieved from Rulezet.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.