Vulnerability-Lookup

FKIE_CVE-2026-97940

Vulnerability from fkie_nvd - Published: 2026-09-25 11:17 - Updated: 2026-09-25 15:18

Severity

7.8 (High) - CVSS:3.1/AV:L/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: ipv6: fix fib6 walker UAF on seq stop ipv6_route_iter_active() treats a walker in FWS_U at the table root as already unlinked. fib6_del_route() can move a still-linked walker into that same state when the current leaf is the last route at the root, so ipv6_route_native_seq_stop() skips fib6_walker_unlink(). The seq private object can then be freed while it remains on net->ipv6.fib6_walkers. A later route deletion walks the dangling list and uses the freed walker. Use the list head as membership state and reinitialize it when unlinking. Keep the existing w->node check so a never-started iterator with a zeroed private object is not treated as linked. The same stop helper is used by /proc/net/ipv6_route and by the BPF ipv6_route iterator. The BPF show path only widens the race.

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/0eede1689610e9eeaf729ba86fd1321799eb91a0
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/19b4ed644d68098cc62ab612727f40d30f43476c
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/4553cfafa8d05c4ce20b1d18f79d9bb3b303fc02
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/b89b691dd00bf39b9ba39ab9446f8c62f419fa7b

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/ip6_fib.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "0eede1689610e9eeaf729ba86fd1321799eb91a0",
              "status": "affected",
              "version": "8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7",
              "versionType": "git"
            },
            {
              "lessThan": "b89b691dd00bf39b9ba39ab9446f8c62f419fa7b",
              "status": "affected",
              "version": "8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7",
              "versionType": "git"
            },
            {
              "lessThan": "4553cfafa8d05c4ce20b1d18f79d9bb3b303fc02",
              "status": "affected",
              "version": "8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7",
              "versionType": "git"
            },
            {
              "lessThan": "19b4ed644d68098cc62ab612727f40d30f43476c",
              "status": "affected",
              "version": "8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/ip6_fib.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.13"
            },
            {
              "lessThan": "3.13",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: fix fib6 walker UAF on seq stop\n\nipv6_route_iter_active() treats a walker in FWS_U at the table root as\nalready unlinked. fib6_del_route() can move a still-linked walker into\nthat same state when the current leaf is the last route at the root,\nso ipv6_route_native_seq_stop() skips fib6_walker_unlink(). The seq\nprivate object can then be freed while it remains on\nnet-\u003eipv6.fib6_walkers. A later route deletion walks the dangling list\nand uses the freed walker.\n\nUse the list head as membership state and reinitialize it when\nunlinking. Keep the existing w-\u003enode check so a never-started iterator\nwith a zeroed private object is not treated as linked.\n\nThe same stop helper is used by /proc/net/ipv6_route and by the BPF\nipv6_route iterator. The BPF show path only widens the race."
    }
  ],
  "id": "CVE-2026-97940",
  "lastModified": "2026-09-25T15:18:02.713",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-09-25T11:17:21.410",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0eede1689610e9eeaf729ba86fd1321799eb91a0"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/19b4ed644d68098cc62ab612727f40d30f43476c"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/4553cfafa8d05c4ce20b1d18f79d9bb3b303fc02"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b89b691dd00bf39b9ba39ab9446f8c62f419fa7b"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

CVE-2026-97940 (GCVE-0-2026-97940)

Vulnerability from cvelistv5 – Published: 2026-09-25 10:22 – Updated: 2026-09-25 14:41

Title

ipv6: fix fib6 walker UAF on seq stop

Summary

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root

References

4 references

URL	Tags
https://git.kernel.org/stable/c/0eede1689610e9eea…
https://git.kernel.org/stable/c/b89b691dd00bf39b9…
https://git.kernel.org/stable/c/4553cfafa8d05c4ce…
https://git.kernel.org/stable/c/19b4ed644d68098cc…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7 , < 0eede1689610e9eeaf729ba86fd1321799eb91a0 (git) Affected: 8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7 , < b89b691dd00bf39b9ba39ab9446f8c62f419fa7b (git) Affected: 8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7 , < 4553cfafa8d05c4ce20b1d18f79d9bb3b303fc02 (git) Affected: 8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7 , < 19b4ed644d68098cc62ab612727f40d30f43476c (git)
Linux	Linux	Affected: 3.13 Unaffected: 0 , < 3.13 (semver) Unaffected: 6.12.111 , ≤ 6.12.* (semver) Unaffected: 6.18.53 , ≤ 6.18.* (semver) Unaffected: 7.2.7 , ≤ 7.2.* (semver) Unaffected: 7.3-rc3 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/ip6_fib.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "0eede1689610e9eeaf729ba86fd1321799eb91a0",
              "status": "affected",
              "version": "8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7",
              "versionType": "git"
            },
            {
              "lessThan": "b89b691dd00bf39b9ba39ab9446f8c62f419fa7b",
              "status": "affected",
              "version": "8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7",
              "versionType": "git"
            },
            {
              "lessThan": "4553cfafa8d05c4ce20b1d18f79d9bb3b303fc02",
              "status": "affected",
              "version": "8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7",
              "versionType": "git"
            },
            {
              "lessThan": "19b4ed644d68098cc62ab612727f40d30f43476c",
              "status": "affected",
              "version": "8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/ip6_fib.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.13"
            },
            {
              "lessThan": "3.13",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.111",
                  "versionStartIncluding": "3.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.53",
                  "versionStartIncluding": "3.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.7",
                  "versionStartIncluding": "3.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc3",
                  "versionStartIncluding": "3.13",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: fix fib6 walker UAF on seq stop\n\nipv6_route_iter_active() treats a walker in FWS_U at the table root as\nalready unlinked. fib6_del_route() can move a still-linked walker into\nthat same state when the current leaf is the last route at the root,\nso ipv6_route_native_seq_stop() skips fib6_walker_unlink(). The seq\nprivate object can then be freed while it remains on\nnet-\u003eipv6.fib6_walkers. A later route deletion walks the dangling list\nand uses the freed walker.\n\nUse the list head as membership state and reinitialize it when\nunlinking. Keep the existing w-\u003enode check so a never-started iterator\nwith a zeroed private object is not treated as linked.\n\nThe same stop helper is used by /proc/net/ipv6_route and by the BPF\nipv6_route iterator. The BPF show path only widens the race."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The bug is reached by a local read() of /proc/net/ipv6_route (ipv6_route_native_seq_stop via ipv6_route_seq_ops, or the BPF ipv6_route iterator) racing a local RTM_DELROUTE netlink request that runs fib6_del_route(). No remote protocol supplies data that causes the missed fib6_walker_unlink().\nAC:L - The attacker controls both sides of the race. One thread reads /proc/net/ipv6_route while another repeatedly adds and deletes the last route in the table root (e.g. ::/0), which moves the linked walker to FWS_U at the root so seq_stop skips the unlink. The attempt can be retried freely.\nPR:L - /proc/net/ipv6_route is created with mode 0 (0444, world-readable). Deleting routes needs CAP_NET_ADMIN only over the namespace, which an unprivileged user gets with unshare -Urn, and net-\u003eipv6.fib6_walkers is per-namespace, so the whole attack runs in an attacker-owned netns.\nUI:N - No victim action is needed. The attacker opens, reads and closes the proc file and issues the route deletions themselves.\nS:U - The use-after-free happens in kernel heap memory and gives kernel-level impact within the same security authority. No VM or hardware isolation boundary is crossed.\nC:H - The freed seq_file private object (struct ipv6_route_iter, holding the fib6_walker) stays on net-\u003eipv6.fib6_walkers. Later FOR_WALKERS loops read w-\u003estate, w-\u003eleaf and w-\u003enode from memory the attacker can reallocate with controlled contents, a UAF usable for kernel memory disclosure.\nI:H - fib6_del_route() and fib6_repair_tree() write w-\u003eleaf, w-\u003estate and w-\u003enode into the freed walker, and list_add/list_del on w-\u003elh write pointers into it. That is a write primitive into a reallocated kernel heap object, usable for corruption and privilege escalation.\nA:H - Any later route deletion or tree repair in that namespace walks the dangling fib6_walkers entry, which causes list corruption or a KASAN/oops crash of the kernel."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-25T14:41:42.075Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/0eede1689610e9eeaf729ba86fd1321799eb91a0"
        },
        {
          "url": "https://git.kernel.org/stable/c/b89b691dd00bf39b9ba39ab9446f8c62f419fa7b"
        },
        {
          "url": "https://git.kernel.org/stable/c/4553cfafa8d05c4ce20b1d18f79d9bb3b303fc02"
        },
        {
          "url": "https://git.kernel.org/stable/c/19b4ed644d68098cc62ab612727f40d30f43476c"
        }
      ],
      "title": "ipv6: fix fib6 walker UAF on seq stop",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-97940",
    "datePublished": "2026-09-25T10:22:52.936Z",
    "dateReserved": "2026-09-25T10:18:58.204Z",
    "dateUpdated": "2026-09-25T14:41:42.075Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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FKIE_CVE-2026-97940

CVE-2026-97940 (GCVE-0-2026-97940)

Tags

Sightings

Nomenclature

Related by attack behaviour