Vulnerability-Lookup

FKIE_CVE-2024-40910

Vulnerability from fkie_nvd - Published: 2024-07-12 13:15 - Updated: 2026-08-04 11:19

Severity

8.8 (High) - CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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: ax25: Fix refcount imbalance on inbound connections When releasing a socket in ax25_release(), we call netdev_put() to decrease the refcount on the associated ax.25 device. However, the execution path for accepting an incoming connection never calls netdev_hold(). This imbalance leads to refcount errors, and ultimately to kernel crashes. A typical call trace for the above situation will start with one of the following errors: refcount_t: decrement hit 0; leaking memory. refcount_t: underflow; use-after-free. And will then have a trace like: Call Trace: <TASK> ? show_regs+0x64/0x70 ? __warn+0x83/0x120 ? refcount_warn_saturate+0xb2/0x100 ? report_bug+0x158/0x190 ? prb_read_valid+0x20/0x30 ? handle_bug+0x3e/0x70 ? exc_invalid_op+0x1c/0x70 ? asm_exc_invalid_op+0x1f/0x30 ? refcount_warn_saturate+0xb2/0x100 ? refcount_warn_saturate+0xb2/0x100 ax25_release+0x2ad/0x360 __sock_release+0x35/0xa0 sock_close+0x19/0x20 [...] On reboot (or any attempt to remove the interface), the kernel gets stuck in an infinite loop: unregister_netdevice: waiting for ax0 to become free. Usage count = 0 This patch corrects these issues by ensuring that we call netdev_hold() and ax25_dev_hold() for new connections in ax25_accept(). This makes the logic leading to ax25_accept() match the logic for ax25_bind(): in both cases we increment the refcount, which is ultimately decremented in ax25_release().

References

URL	Tags
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/3c34fb0bd4a4237592c5ecb5b2e2531900c55774	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/52100fd74ad07b53a4666feafff1cd11436362d3	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/a723a6c8d4831cc8e2c7b0c9f3f0c010d4671964	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/f4df9d6c8d4e4c818252b0419c2165d66eabd4eb	Patch
af854a3a-2127-422b-91ae-364da2661108	https://git.kernel.org/stable/c/3c34fb0bd4a4237592c5ecb5b2e2531900c55774	Patch
af854a3a-2127-422b-91ae-364da2661108	https://git.kernel.org/stable/c/52100fd74ad07b53a4666feafff1cd11436362d3	Patch
af854a3a-2127-422b-91ae-364da2661108	https://git.kernel.org/stable/c/a723a6c8d4831cc8e2c7b0c9f3f0c010d4671964	Patch
af854a3a-2127-422b-91ae-364da2661108	https://git.kernel.org/stable/c/f4df9d6c8d4e4c818252b0419c2165d66eabd4eb	Patch
af854a3a-2127-422b-91ae-364da2661108	https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html

Impacted products

Vendor	Product	Version
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	6.10
linux	linux_kernel	6.10

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ax25/af_ax25.c"
          ],
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              "version": "de55a1338e6a48ff1e41ea8db1432496fbe2a62b",
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      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nax25: Fix refcount imbalance on inbound connections\n\nWhen releasing a socket in ax25_release(), we call netdev_put() to\ndecrease the refcount on the associated ax.25 device. However, the\nexecution path for accepting an incoming connection never calls\nnetdev_hold(). This imbalance leads to refcount errors, and ultimately\nto kernel crashes.\n\nA typical call trace for the above situation will start with one of the\nfollowing errors:\n\n    refcount_t: decrement hit 0; leaking memory.\n    refcount_t: underflow; use-after-free.\n\nAnd will then have a trace like:\n\n    Call Trace:\n    \u003cTASK\u003e\n    ? show_regs+0x64/0x70\n    ? __warn+0x83/0x120\n    ? refcount_warn_saturate+0xb2/0x100\n    ? report_bug+0x158/0x190\n    ? prb_read_valid+0x20/0x30\n    ? handle_bug+0x3e/0x70\n    ? exc_invalid_op+0x1c/0x70\n    ? asm_exc_invalid_op+0x1f/0x30\n    ? refcount_warn_saturate+0xb2/0x100\n    ? refcount_warn_saturate+0xb2/0x100\n    ax25_release+0x2ad/0x360\n    __sock_release+0x35/0xa0\n    sock_close+0x19/0x20\n    [...]\n\nOn reboot (or any attempt to remove the interface), the kernel gets\nstuck in an infinite loop:\n\n    unregister_netdevice: waiting for ax0 to become free. Usage count = 0\n\nThis patch corrects these issues by ensuring that we call netdev_hold()\nand ax25_dev_hold() for new connections in ax25_accept(). This makes the\nlogic leading to ax25_accept() match the logic for ax25_bind(): in both\ncases we increment the refcount, which is ultimately decremented in\nax25_release()."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se resolvi\u00f3 la siguiente vulnerabilidad: ax25: corrige el desequilibrio de recuento en conexiones entrantes Al liberar un socket en ax25_release(), llamamos a netdev_put() para disminuir el recuento en el dispositivo ax.25 asociado. Sin embargo, la ruta de ejecuci\u00f3n para aceptar una conexi\u00f3n entrante nunca llama a netdev_hold(). Este desequilibrio conduce a errores de recuento y, en \u00faltima instancia, a fallos del kernel. Un seguimiento de llamada t\u00edpico para la situaci\u00f3n anterior comenzar\u00e1 con uno de los siguientes errores: refcount_t: decrement hit 0; p\u00e9rdida de memoria. refcount_t: desbordamiento insuficiente; use-after-free. Y luego tendr\u00e1 un seguimiento como: Call Trace:  ? show_regs+0x64/0x70? __advertir+0x83/0x120 ? refcount_warn_saturate+0xb2/0x100? report_bug+0x158/0x190? prb_read_valid+0x20/0x30? handle_bug+0x3e/0x70? exc_invalid_op+0x1c/0x70? asm_exc_invalid_op+0x1f/0x30? refcount_warn_saturate+0xb2/0x100? refcount_warn_saturate+0xb2/0x100 ax25_release+0x2ad/0x360 __sock_release+0x35/0xa0 sock_close+0x19/0x20 [...] Al reiniciar (o cualquier intento de eliminar la interfaz), el kernel se atasca en un bucle infinito: unregister_netdevice: esperando ax0 para quedar libre. Recuento de uso = 0 Este parche corrige estos problemas asegurando que llamemos a netdev_hold() y ax25_dev_hold() para nuevas conexiones en ax25_accept(). Esto hace que la l\u00f3gica que conduce a ax25_accept() coincida con la l\u00f3gica de ax25_bind(): en ambos casos incrementamos el refcount, que finalmente disminuye en ax25_release()."
    }
  ],
  "id": "CVE-2024-40910",
  "lastModified": "2026-08-04T11:19:04.370",
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}

CVE-2024-40910 (GCVE-0-2024-40910)

Vulnerability from cvelistv5 – Published: 2024-07-12 12:20 – Updated: 2026-08-05 11:33

Title

ax25: Fix refcount imbalance on inbound connections

Summary

Severity

8.8 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2024-09-10 17:06 UTC

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 7033 records in the last 180 days details

References

5 references

URL	Tags
https://git.kernel.org/stable/c/f4df9d6c8d4e4c818…
https://git.kernel.org/stable/c/52100fd74ad07b53a…
https://git.kernel.org/stable/c/a723a6c8d4831cc8e…
https://git.kernel.org/stable/c/3c34fb0bd4a423759…
https://lists.debian.org/debian-lts-announce/2025…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 9fd75b66b8f68498454d685dc4ba13192ae069b0 , < f4df9d6c8d4e4c818252b0419c2165d66eabd4eb (git) Affected: 9fd75b66b8f68498454d685dc4ba13192ae069b0 , < 52100fd74ad07b53a4666feafff1cd11436362d3 (git) Affected: 9fd75b66b8f68498454d685dc4ba13192ae069b0 , < a723a6c8d4831cc8e2c7b0c9f3f0c010d4671964 (git) Affected: 9fd75b66b8f68498454d685dc4ba13192ae069b0 , < 3c34fb0bd4a4237592c5ecb5b2e2531900c55774 (git) Affected: c44a453ffe16eb08acdc6129ac4fa0192dbc0456 (git) Affected: de55a1338e6a48ff1e41ea8db1432496fbe2a62b (git) Affected: 9e1e088a57c23251f1cfe9601bbd90ade2ea73b9 (git) Affected: b20a5ab0f5fb175750c6bafd4cf12daccf00c738 (git) Affected: 452ae92b99062d2f6a34324eaf705a3b7eac9f8b (git) Affected: 534156dd4ed768e30a43de0036f45dca7c54818f (git) Affected: 4.14.277 , < 4.15 (semver) Affected: 4.19.240 , < 4.20 (semver) Affected: 5.4.190 , < 5.5 (semver) Affected: 5.10.112 , < 5.11 (semver) Affected: 5.15.35 , < 5.16 (semver) Affected: 5.17.2 , < 5.18 (semver)
Linux	Linux	Affected: 5.18 Unaffected: 0 , < 5.18 (semver) Unaffected: 6.1.95 , ≤ 6.1.* (semver) Unaffected: 6.6.35 , ≤ 6.6.* (semver) Unaffected: 6.9.6 , ≤ 6.9.* (semver) Unaffected: 6.10 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

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          "dateUpdated": "2024-09-11T17:34:37.278Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ax25/af_ax25.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "f4df9d6c8d4e4c818252b0419c2165d66eabd4eb",
              "status": "affected",
              "version": "9fd75b66b8f68498454d685dc4ba13192ae069b0",
              "versionType": "git"
            },
            {
              "lessThan": "52100fd74ad07b53a4666feafff1cd11436362d3",
              "status": "affected",
              "version": "9fd75b66b8f68498454d685dc4ba13192ae069b0",
              "versionType": "git"
            },
            {
              "lessThan": "a723a6c8d4831cc8e2c7b0c9f3f0c010d4671964",
              "status": "affected",
              "version": "9fd75b66b8f68498454d685dc4ba13192ae069b0",
              "versionType": "git"
            },
            {
              "lessThan": "3c34fb0bd4a4237592c5ecb5b2e2531900c55774",
              "status": "affected",
              "version": "9fd75b66b8f68498454d685dc4ba13192ae069b0",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "c44a453ffe16eb08acdc6129ac4fa0192dbc0456",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "de55a1338e6a48ff1e41ea8db1432496fbe2a62b",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "9e1e088a57c23251f1cfe9601bbd90ade2ea73b9",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "b20a5ab0f5fb175750c6bafd4cf12daccf00c738",
              "versionType": "git"
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              "status": "affected",
              "version": "452ae92b99062d2f6a34324eaf705a3b7eac9f8b",
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            },
            {
              "status": "affected",
              "version": "534156dd4ed768e30a43de0036f45dca7c54818f",
              "versionType": "git"
            },
            {
              "lessThan": "4.15",
              "status": "affected",
              "version": "4.14.277",
              "versionType": "semver"
            },
            {
              "lessThan": "4.20",
              "status": "affected",
              "version": "4.19.240",
              "versionType": "semver"
            },
            {
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              "status": "affected",
              "version": "5.4.190",
              "versionType": "semver"
            },
            {
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              "status": "affected",
              "version": "5.10.112",
              "versionType": "semver"
            },
            {
              "lessThan": "5.16",
              "status": "affected",
              "version": "5.15.35",
              "versionType": "semver"
            },
            {
              "lessThan": "5.18",
              "status": "affected",
              "version": "5.17.2",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.18"
            },
            {
              "lessThan": "5.18",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.95",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.35",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.9.*",
              "status": "unaffected",
              "version": "6.9.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.10",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.95",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.35",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.9.6",
                  "versionStartIncluding": "5.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.10",
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                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "4.14.277",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "4.19.240",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "5.4.190",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "5.10.112",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "5.15.35",
                  "vulnerable": true
                },
                {
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                  "versionStartIncluding": "5.17.2",
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nax25: Fix refcount imbalance on inbound connections\n\nWhen releasing a socket in ax25_release(), we call netdev_put() to\ndecrease the refcount on the associated ax.25 device. However, the\nexecution path for accepting an incoming connection never calls\nnetdev_hold(). This imbalance leads to refcount errors, and ultimately\nto kernel crashes.\n\nA typical call trace for the above situation will start with one of the\nfollowing errors:\n\n    refcount_t: decrement hit 0; leaking memory.\n    refcount_t: underflow; use-after-free.\n\nAnd will then have a trace like:\n\n    Call Trace:\n    \u003cTASK\u003e\n    ? show_regs+0x64/0x70\n    ? __warn+0x83/0x120\n    ? refcount_warn_saturate+0xb2/0x100\n    ? report_bug+0x158/0x190\n    ? prb_read_valid+0x20/0x30\n    ? handle_bug+0x3e/0x70\n    ? exc_invalid_op+0x1c/0x70\n    ? asm_exc_invalid_op+0x1f/0x30\n    ? refcount_warn_saturate+0xb2/0x100\n    ? refcount_warn_saturate+0xb2/0x100\n    ax25_release+0x2ad/0x360\n    __sock_release+0x35/0xa0\n    sock_close+0x19/0x20\n    [...]\n\nOn reboot (or any attempt to remove the interface), the kernel gets\nstuck in an infinite loop:\n\n    unregister_netdevice: waiting for ax0 to become free. Usage count = 0\n\nThis patch corrects these issues by ensuring that we call netdev_hold()\nand ax25_dev_hold() for new connections in ax25_accept(). This makes the\nlogic leading to ax25_accept() match the logic for ax25_bind(): in both\ncases we increment the refcount, which is ultimately decremented in\nax25_release()."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:A - The imbalance is created by an inbound SABM processed in `ax25_rcv()`, reached from the link-layer handlers `ax25_kiss_rcv()` (RF/KISS TNC, 6pack, scc) and `bpq_rcv()` (AX.25 encapsulated in Ethernet, ethertype 0x08FF), so any station on the shared radio channel or the local Ethernet segment can trigger it. AX.25 frames are not IP-routable by the kernel itself, so this is adjacent rather than full network reach.\nAC:L - The attacker simply connects and disconnects repeatedly; each accepted-then-closed session deterministically drops one unheld netdev reference and one unheld ax25_dev reference, and only a couple of iterations are needed to drive `ax25_dev-\u003erefcount` to zero. No race, no memory-layout precondition, and the attacker controls the repetition count.\nPR:N - AX.25 has no authentication whatsoever \u2014 an unauthenticated remote station only needs to send a SABM to a listening callsign on a node/BBS/ax25d service. No credentials or local account on the victim are required.\nUI:N - A listening AX.25 service accepts inbound connections automatically and closes the session socket when the peer disconnects, which is exactly the release path that performs the unbalanced `netdev_put()`/`ax25_dev_put()`. No operator action is needed.\nS:U - The corruption is confined to kernel memory within the same security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - `ax25_dev_put()` frees the `ax25_dev` while `dev-\u003eax25_ptr` and `ax25_dev_list` still reference it, so subsequent received frames read attacker-refillable freed slab memory (`values[]`, `forward`, `sysheader`), and the netdev refcount underflow can free `struct net_device` while sockets still point at it \u2014 a use-after-free that is leverageable for kernel memory disclosure.\nI:H - The freed `ax25_dev` embeds a `timer_list` (DAMA slave timer with a function pointer) and a `list_head` that are still armed/linked, plus a `net_device *forward` used on the transmit path; reclaiming the slab yields write and control-flow-hijack primitives typical of a use-after-free.\nA:H - The commit documents kernel crashes from the refcount underflow, and on interface teardown or reboot the kernel spins forever in `unregister_netdevice: waiting for ax0 to become free. Usage count = 0` with RTNL held \u2014 a permanent, remotely inducible hang in addition to the UAF oops."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T11:33:57.773Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f4df9d6c8d4e4c818252b0419c2165d66eabd4eb"
        },
        {
          "url": "https://git.kernel.org/stable/c/52100fd74ad07b53a4666feafff1cd11436362d3"
        },
        {
          "url": "https://git.kernel.org/stable/c/a723a6c8d4831cc8e2c7b0c9f3f0c010d4671964"
        },
        {
          "url": "https://git.kernel.org/stable/c/3c34fb0bd4a4237592c5ecb5b2e2531900c55774"
        }
      ],
      "title": "ax25: Fix refcount imbalance on inbound connections",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2024-40910",
    "datePublished": "2024-07-12T12:20:49.085Z",
    "dateReserved": "2024-07-12T12:17:45.580Z",
    "dateUpdated": "2026-08-05T11:33:57.773Z",
    "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.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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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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