macsec: sync features on RTM_NEWLINK

{
  "id": "6d3a80fd7f8f232ce8543a9af396c2ce1ee33cafca8fac1849d54f5a2d0395d2",
  "url": "https://osv.dev/vulnerability/CVE-2025-39874",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "macsec: sync features on RTM_NEWLINK",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: macsec: sync features on RTM_NEWLINK Syzkaller managed to lock the lower device via ETHTOOL_SFEATURES: netdev_lock include/linux/netdevice.h:2761 [inline] netdev_lock_ops include/net/netdev_lock.h:42 [inline] netdev_sync_lower_features net/core/dev.c:10649 [inline] __netdev_update_features+0xcb1/0x1be0 net/core/dev.c:10819 netdev_update_features+0x6d/0xe0 net/core/dev.c:10876 macsec_notify+0x2f5/0x660 drivers/net/macsec.c:4533 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85 call_netdevice_notifiers_extack net/core/dev.c:2267 [inline] call_netdevice_notifiers net/core/dev.c:2281 [inline] netdev_features_change+0x85/0xc0 net/core/dev.c:1570 __dev_ethtool net/ethtool/ioctl.c:3469 [inline] dev_ethtool+0x1536/0x19b0 net/ethtool/ioctl.c:3502 dev_ioctl+0x392/0x1150 net/core/dev_ioctl.c:759 It happens because lower features are out of sync with the upper: __dev_ethtool (real_dev) netdev_lock_ops(real_dev) ETHTOOL_SFEATURES __netdev_features_change netdev_sync_upper_features disable LRO on the lower if (old_features != dev->features) netdev_features_change fires NETDEV_FEAT_CHANGE macsec_notify NETDEV_FEAT_CHANGE netdev_update_features (for each macsec dev) netdev_sync_lower_features if (upper_features != lower_features) netdev_lock_ops(lower) # lower == real_dev stuck ... netdev_unlock_ops(real_dev) Per commit af5f54b0ef9e (\"net: Lock lower level devices when updating features\"), we elide the lock/unlock when th",
    "evidence": "osv:CVE-2025-39874",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.16.8",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "CVE-2025-39874",
      "aliases": [
        "CVE-2025-39874"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "7e4d784f5810bba76c4593791028e13cce4af547"
                },
                {
                  "fixed": "d7624629ccf47135c65fef0701fa0d9a115b87f3"
                },
                {
                  "fixed": "0f82c3ba66c6b2e3cde0f255156a753b108ee9dc"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-39874.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.15.0"
                },
                {
                  "fixed": "6.16.8"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-39874.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:31.180335430Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/0f82c3ba66c6b2e3cde0f255156a753b108ee9dc",
        "https://git.kernel.org/stable/c/d7624629ccf47135c65fef0701fa0d9a115b87f3",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/39xxx/CVE-2025-39874.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-39874",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/39xxx/CVE-2025-39874.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-39874",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 498253,
  "published_at": "2025-09-23T06:00:46.69+00:00"
}