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

FKIE_CVE-2026-23143

Vulnerability from fkie_nvd - Published: 2026-02-14 16:15 - Updated: 2026-06-17 10:20
Severity
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: virtio_net: Fix misalignment bug in struct virtnet_info Use the new TRAILING_OVERLAP() helper to fix a misalignment bug along with the following warning: drivers/net/virtio_net.c:429:46: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] This helper creates a union between a flexible-array member (FAM) and a set of members that would otherwise follow it (in this case `u8 rss_hash_key_data[VIRTIO_NET_RSS_MAX_KEY_SIZE];`). This overlays the trailing members (rss_hash_key_data) onto the FAM (hash_key_data) while keeping the FAM and the start of MEMBERS aligned. The static_assert() ensures this alignment remains. Notice that due to tail padding in flexible `struct virtio_net_rss_config_trailer`, `rss_trailer.hash_key_data` (at offset 83 in struct virtnet_info) and `rss_hash_key_data` (at offset 84 in struct virtnet_info) are misaligned by one byte. See below: struct virtio_net_rss_config_trailer { __le16 max_tx_vq; /* 0 2 */ __u8 hash_key_length; /* 2 1 */ __u8 hash_key_data[]; /* 3 0 */ /* size: 4, cachelines: 1, members: 3 */ /* padding: 1 */ /* last cacheline: 4 bytes */ }; struct virtnet_info { ... struct virtio_net_rss_config_trailer rss_trailer; /* 80 4 */ /* XXX last struct has 1 byte of padding */ u8 rss_hash_key_data[40]; /* 84 40 */ ... /* size: 832, cachelines: 13, members: 48 */ /* sum members: 801, holes: 8, sum holes: 31 */ /* paddings: 2, sum paddings: 5 */ }; After changes, those members are correctly aligned at offset 795: struct virtnet_info { ... union { struct virtio_net_rss_config_trailer rss_trailer; /* 792 4 */ struct { unsigned char __offset_to_hash_key_data[3]; /* 792 3 */ u8 rss_hash_key_data[40]; /* 795 40 */ }; /* 792 43 */ }; /* 792 44 */ ... /* size: 840, cachelines: 14, members: 47 */ /* sum members: 801, holes: 8, sum holes: 35 */ /* padding: 4 */ /* paddings: 1, sum paddings: 4 */ /* last cacheline: 8 bytes */ }; As a result, the RSS key passed to the device is shifted by 1 byte: the last byte is cut off, and instead a (possibly uninitialized) byte is added at the beginning. As a last note `struct virtio_net_rss_config_hdr *rss_hdr;` is also moved to the end, since it seems those three members should stick around together. :)
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4156c3745f06bc197094b9ee97a9584e69ed00bfPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ae48108c2310f1dd700e0dbb655c2f1d92ed00fcPatch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel 6.19
linux linux_kernel 6.19
linux linux_kernel 6.19
linux linux_kernel 6.19
linux linux_kernel 6.19
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/virtio_net.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "ae48108c2310f1dd700e0dbb655c2f1d92ed00fc",
              "status": "affected",
              "version": "ed3100e90d0d120a045a551b85eb43cf2527e885",
              "versionType": "git"
            },
            {
              "lessThan": "4156c3745f06bc197094b9ee97a9584e69ed00bf",
              "status": "affected",
              "version": "ed3100e90d0d120a045a551b85eb43cf2527e885",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "4c47aff10f6f0a2506dc2126c17ccd4c42bfa211",
              "versionType": "git"
            },
            {
              "lessThan": "6.13",
              "status": "affected",
              "version": "6.12.91",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/virtio_net.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
            },
            {
              "lessThan": "6.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.19",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "2446B98C-005E-4681-A566-03D3F408B450",
              "versionEndExcluding": "6.18.7",
              "versionStartIncluding": "6.15",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.19:rc1:*:*:*:*:*:*",
              "matchCriteriaId": "17B67AA7-40D6-4AFA-8459-F200F3D7CFD1",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.19:rc2:*:*:*:*:*:*",
              "matchCriteriaId": "C47E4CC9-C826-4FA9-B014-7FE3D9B318B2",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.19:rc3:*:*:*:*:*:*",
              "matchCriteriaId": "F71D92C0-C023-48BD-B3B6-70B638EEE298",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.19:rc4:*:*:*:*:*:*",
              "matchCriteriaId": "13580667-0A98-40CC-B29F-D12790B91BDB",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.19:rc5:*:*:*:*:*:*",
              "matchCriteriaId": "CAD1FED7-CF48-47BF-AC7D-7B6FA3C065FC",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvirtio_net: Fix misalignment bug in struct virtnet_info\n\nUse the new TRAILING_OVERLAP() helper to fix a misalignment bug\nalong with the following warning:\n\ndrivers/net/virtio_net.c:429:46: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]\n\nThis helper creates a union between a flexible-array member (FAM)\nand a set of members that would otherwise follow it (in this case\n`u8 rss_hash_key_data[VIRTIO_NET_RSS_MAX_KEY_SIZE];`). This\noverlays the trailing members (rss_hash_key_data) onto the FAM\n(hash_key_data) while keeping the FAM and the start of MEMBERS aligned.\nThe static_assert() ensures this alignment remains.\n\nNotice that due to tail padding in flexible `struct\nvirtio_net_rss_config_trailer`, `rss_trailer.hash_key_data`\n(at offset 83 in struct virtnet_info) and `rss_hash_key_data` (at\noffset 84 in struct virtnet_info) are misaligned by one byte. See\nbelow:\n\nstruct virtio_net_rss_config_trailer {\n        __le16                     max_tx_vq;            /*     0     2 */\n        __u8                       hash_key_length;      /*     2     1 */\n        __u8                       hash_key_data[];      /*     3     0 */\n\n        /* size: 4, cachelines: 1, members: 3 */\n        /* padding: 1 */\n        /* last cacheline: 4 bytes */\n};\n\nstruct virtnet_info {\n...\n        struct virtio_net_rss_config_trailer rss_trailer; /*    80     4 */\n\n        /* XXX last struct has 1 byte of padding */\n\n        u8                         rss_hash_key_data[40]; /*    84    40 */\n...\n        /* size: 832, cachelines: 13, members: 48 */\n        /* sum members: 801, holes: 8, sum holes: 31 */\n        /* paddings: 2, sum paddings: 5 */\n};\n\nAfter changes, those members are correctly aligned at offset 795:\n\nstruct virtnet_info {\n...\n        union {\n                struct virtio_net_rss_config_trailer rss_trailer; /*   792     4 */\n                struct {\n                        unsigned char __offset_to_hash_key_data[3]; /*   792     3 */\n                        u8         rss_hash_key_data[40]; /*   795    40 */\n                };                                       /*   792    43 */\n        };                                               /*   792    44 */\n...\n        /* size: 840, cachelines: 14, members: 47 */\n        /* sum members: 801, holes: 8, sum holes: 35 */\n        /* padding: 4 */\n        /* paddings: 1, sum paddings: 4 */\n        /* last cacheline: 8 bytes */\n};\n\nAs a result, the RSS key passed to the device is shifted by 1\nbyte: the last byte is cut off, and instead a (possibly\nuninitialized) byte is added at the beginning.\n\nAs a last note `struct virtio_net_rss_config_hdr *rss_hdr;` is also\nmoved to the end, since it seems those three members should stick\naround together. :)"
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nvirtio_net: Corrige un error de desalineaci\u00f3n en la estructura virtnet_info\n\nUsa el nuevo ayudante TRAILING_OVERLAP() para corregir un error de desalineaci\u00f3n junto con la siguiente advertencia:\n\ndrivers/net/virtio_net.c:429:46: advertencia: la estructura que contiene un miembro de array flexible no est\u00e1 al final de otra estructura [-Wflex-array-member-not-at-end]\n\nEste ayudante crea una uni\u00f3n entre un miembro de array flexible (FAM) y un conjunto de miembros que de otro modo lo seguir\u00edan (en este caso \u0027u8 rss_hash_key_data[VIRTIO_NET_RSS_MAX_KEY_SIZE];\u0027). Esto superpone los miembros finales (rss_hash_key_data) sobre el FAM (hash_key_data) mientras mantiene el FAM y el inicio de los MIEMBROS alineados. El static_assert() asegura que esta alineaci\u00f3n se mantenga.\n\nN\u00f3tese que debido al relleno de cola en la estructura flexible \u0027struct virtio_net_rss_config_trailer\u0027, \u0027rss_trailer.hash_key_data\u0027 (en el desplazamiento 83 en la estructura virtnet_info) y \u0027rss_hash_key_data\u0027 (en el desplazamiento 84 en la estructura virtnet_info) est\u00e1n desalineados por un byte. Ver a continuaci\u00f3n:\n\n```\nstruct virtio_net_rss_config_trailer {\n        __le16                     max_tx_vq;            /*     0     2 */\n        __u8                       hash_key_length;      /*     2     1 */\n        __u8                       hash_key_data[];      /*     3     0 */\n\n        /* size: 4, cachelines: 1, members: 3 */\n        /* padding: 1 */\n        /* last cacheline: 4 bytes */\n};\n```\n\n```\nstruct virtnet_info {\n...\n        struct virtio_net_rss_config_trailer rss_trailer; /*    80     4 */\n\n        /* XXX last struct has 1 byte of padding */\n\n        u8                         rss_hash_key_data[40]; /*    84    40 */\n...\n        /* size: 832, cachelines: 13, members: 48 */\n        /* sum members: 801, holes: 8, sum holes: 31 */\n        /* paddings: 2, sum paddings: 5 */\n};\n```\n\nDespu\u00e9s de los cambios, esos miembros est\u00e1n correctamente alineados en el desplazamiento 795:\n\n```\nstruct virtnet_info {\n...\n        union {\n                struct virtio_net_rss_config_trailer rss_trailer; /*   792     4 */\n                struct {\n                        unsigned char __offset_to_hash_key_data[3]; /*   792     3 */\n                        u8         rss_hash_key_data[40]; /*   795    40 */\n                };                                       /*   792    43 */\n        };                                               /*   792    44 */\n...\n        /* size: 840, cachelines: 14, members: 47 */\n        /* sum members: 801, holes: 8, sum holes: 35 */\n        /* padding: 4 */\n        /* paddings: 1, sum paddings: 4 */\n        /* last cacheline: 8 bytes */\n};\n```\n\nComo resultado, la clave RSS pasada al dispositivo se desplaza 1 byte: el \u00faltimo byte se corta y, en su lugar, se a\u00f1ade un byte (posiblemente no inicializado) al principio.\n\nComo \u00faltima nota, \u0027struct virtio_net_rss_config_hdr *rss_hdr;\u0027 tambi\u00e9n se mueve al final, ya que parece que esos tres miembros deber\u00edan permanecer juntos. :)"
    }
  ],
  "id": "CVE-2026-23143",
  "lastModified": "2026-06-17T10:20:58.683",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2026-02-14T16:15:54.383",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/4156c3745f06bc197094b9ee97a9584e69ed00bf"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/ae48108c2310f1dd700e0dbb655c2f1d92ed00fc"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}



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.