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GHSA-6WC5-2MJJ-PMR6

Vulnerability from github – Published: 2026-07-19 12:30 – Updated: 2026-07-20 15:31

Details

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

net: ip_gre: require CAP_NET_ADMIN in the device netns for changelink

A tunnel changelink() operates on at most two netns, dev_net(dev) and the tunnel link netns t->net. They differ once the device is created in or moved to a netns other than the one the request runs in. The rtnl changelink path checks CAP_NET_ADMIN only against dev_net(dev), so a caller privileged there but not in t->net can rewrite a tunnel that lives in t->net.

Add rtnl_dev_link_net_capable() next to rtnl_get_net_ns_capable() in net/core/rtnetlink.c. It requires CAP_NET_ADMIN in the link netns and is skipped when the link netns is dev_net(dev), where the rtnl path already checked it. The other patches in this series use the same helper.

Gate ipgre_changelink() and erspan_changelink() with it, at the top of the op before any attribute is parsed, because the parsers update live tunnel fields first. ipgre_netlink_parms() sets t->collect_md before ip_tunnel_changelink() runs.

Commit 8b484efd5cb4 ("ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate().") added the same check on the ioctl path. This adds it on RTM_NEWLINK.

Severity

8.8 (High)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-63829"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-19T12:16:56Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ip_gre: require CAP_NET_ADMIN in the device netns for changelink\n\nA tunnel changelink() operates on at most two netns, dev_net(dev) and\nthe tunnel link netns t-\u003enet. They differ once the device is created in\nor moved to a netns other than the one the request runs in. The rtnl\nchangelink path checks CAP_NET_ADMIN only against dev_net(dev), so a\ncaller privileged there but not in t-\u003enet can rewrite a tunnel that\nlives in t-\u003enet.\n\nAdd rtnl_dev_link_net_capable() next to rtnl_get_net_ns_capable() in\nnet/core/rtnetlink.c. It requires CAP_NET_ADMIN in the link netns and is\nskipped when the link netns is dev_net(dev), where the rtnl path already\nchecked it. The other patches in this series use the same helper.\n\nGate ipgre_changelink() and erspan_changelink() with it, at the top of\nthe op before any attribute is parsed, because the parsers update live\ntunnel fields first. ipgre_netlink_parms() sets t-\u003ecollect_md before\nip_tunnel_changelink() runs.\n\nCommit 8b484efd5cb4 (\"ip6: vti: Use ip6_tnl.net in\nvti6_siocdevprivate().\") added the same check on the ioctl path. This\nadds it on RTM_NEWLINK.",
  "id": "GHSA-6wc5-2mjj-pmr6",
  "modified": "2026-07-20T15:31:47Z",
  "published": "2026-07-19T12:30:24Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63829"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1697957eb0971d420dde42862b88eb43506a1105"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/47b5d3d506609b08b2e1f7c14f0b681a1953d572"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8165f7ff57d9667d2bb477ef6af83ede7fed4ad7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9831bc9ecb402957810c2045c663fbfe9b09e296"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-63829 (GCVE-0-2026-63829)

Vulnerability from cvelistv5 – Published: 2026-07-19 12:02 – Updated: 2026-07-20 13:40

Title

net: ip_gre: require CAP_NET_ADMIN in the device netns for changelink

Summary

In the Linux kernel, the following vulnerability has been resolved: net: ip_gre: require CAP_NET_ADMIN in the device netns for changelink A tunnel changelink() operates on at most two netns, dev_net(dev) and the tunnel link netns t->net. They differ once the device is created in or moved to a netns other than the one the request runs in. The rtnl changelink path checks CAP_NET_ADMIN only against dev_net(dev), so a caller privileged there but not in t->net can rewrite a tunnel that lives in t->net. Add rtnl_dev_link_net_capable() next to rtnl_get_net_ns_capable() in net/core/rtnetlink.c. It requires CAP_NET_ADMIN in the link netns and is skipped when the link netns is dev_net(dev), where the rtnl path already checked it. The other patches in this series use the same helper. Gate ipgre_changelink() and erspan_changelink() with it, at the top of the op before any attribute is parsed, because the parsers update live tunnel fields first. ipgre_netlink_parms() sets t->collect_md before ip_tunnel_changelink() runs. Commit 8b484efd5cb4 ("ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate().") added the same check on the ioctl path. This adds it on RTM_NEWLINK.

Severity

8.8 (High)


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

Assigner

Linux

References

4 references

URL	Tags
https://git.kernel.org/stable/c/9831bc9ecb4029578…
https://git.kernel.org/stable/c/1697957eb0971d420…
https://git.kernel.org/stable/c/47b5d3d506609b08b…
https://git.kernel.org/stable/c/8165f7ff57d9667d2…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: b57708add31494175be741ed3fd24023b50c3423 , < 9831bc9ecb402957810c2045c663fbfe9b09e296 (git) Affected: b57708add31494175be741ed3fd24023b50c3423 , < 1697957eb0971d420dde42862b88eb43506a1105 (git) Affected: b57708add31494175be741ed3fd24023b50c3423 , < 47b5d3d506609b08b2e1f7c14f0b681a1953d572 (git) Affected: b57708add31494175be741ed3fd24023b50c3423 , < 8165f7ff57d9667d2bb477ef6af83ede7fed4ad7 (git)
Linux	Linux	Affected: 3.16 Unaffected: 0 , < 3.16 (semver) Unaffected: 6.12.95 , ≤ 6.12.* (semver) Unaffected: 6.18.38 , ≤ 6.18.* (semver) Unaffected: 7.1.3 , ≤ 7.1.* (semver) Unaffected: 7.2-rc1 , ≤ * (original_commit_for_fix)

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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/net/rtnetlink.h",
            "net/core/rtnetlink.c",
            "net/ipv4/ip_gre.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "9831bc9ecb402957810c2045c663fbfe9b09e296",
              "status": "affected",
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              "versionType": "git"
            },
            {
              "lessThan": "1697957eb0971d420dde42862b88eb43506a1105",
              "status": "affected",
              "version": "b57708add31494175be741ed3fd24023b50c3423",
              "versionType": "git"
            },
            {
              "lessThan": "47b5d3d506609b08b2e1f7c14f0b681a1953d572",
              "status": "affected",
              "version": "b57708add31494175be741ed3fd24023b50c3423",
              "versionType": "git"
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            {
              "lessThan": "8165f7ff57d9667d2bb477ef6af83ede7fed4ad7",
              "status": "affected",
              "version": "b57708add31494175be741ed3fd24023b50c3423",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "include/net/rtnetlink.h",
            "net/core/rtnetlink.c",
            "net/ipv4/ip_gre.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.16"
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              "lessThan": "3.16",
              "status": "unaffected",
              "version": "0",
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              "status": "unaffected",
              "version": "6.12.95",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "6.18.38",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.95",
                  "versionStartIncluding": "3.16",
                  "vulnerable": true
                },
                {
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                  "vulnerable": true
                },
                {
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                {
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ip_gre: require CAP_NET_ADMIN in the device netns for changelink\n\nA tunnel changelink() operates on at most two netns, dev_net(dev) and\nthe tunnel link netns t-\u003enet. They differ once the device is created in\nor moved to a netns other than the one the request runs in. The rtnl\nchangelink path checks CAP_NET_ADMIN only against dev_net(dev), so a\ncaller privileged there but not in t-\u003enet can rewrite a tunnel that\nlives in t-\u003enet.\n\nAdd rtnl_dev_link_net_capable() next to rtnl_get_net_ns_capable() in\nnet/core/rtnetlink.c. It requires CAP_NET_ADMIN in the link netns and is\nskipped when the link netns is dev_net(dev), where the rtnl path already\nchecked it. The other patches in this series use the same helper.\n\nGate ipgre_changelink() and erspan_changelink() with it, at the top of\nthe op before any attribute is parsed, because the parsers update live\ntunnel fields first. ipgre_netlink_parms() sets t-\u003ecollect_md before\nip_tunnel_changelink() runs.\n\nCommit 8b484efd5cb4 (\"ip6: vti: Use ip6_tnl.net in\nvti6_siocdevprivate().\") added the same check on the ioctl path. This\nadds it on RTM_NEWLINK."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          }
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        "dateUpdated": "2026-07-20T13:40:32.618Z",
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          "url": "https://git.kernel.org/stable/c/47b5d3d506609b08b2e1f7c14f0b681a1953d572"
        },
        {
          "url": "https://git.kernel.org/stable/c/8165f7ff57d9667d2bb477ef6af83ede7fed4ad7"
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      ],
      "title": "net: ip_gre: require CAP_NET_ADMIN in the device netns for changelink",
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        "engine": "bippy-1.2.0"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-63829",
    "datePublished": "2026-07-19T12:02:23.191Z",
    "dateReserved": "2026-07-19T07:54:57.014Z",
    "dateUpdated": "2026-07-20T13:40:32.618Z",
    "state": "PUBLISHED"
  },
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}

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.

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.

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GHSA-6WC5-2MJJ-PMR6

CVE-2026-63829 (GCVE-0-2026-63829)

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Nomenclature