Vulnerability-Lookup

FKIE_CVE-2025-21796

Vulnerability from fkie_nvd - Published: 2025-02-27 03:15 - Updated: 2026-07-30 06:21

Severity

9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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: nfsd: clear acl_access/acl_default after releasing them If getting acl_default fails, acl_access and acl_default will be released simultaneously. However, acl_access will still retain a pointer pointing to the released posix_acl, which will trigger a WARNING in nfs3svc_release_getacl like this: ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 26 PID: 3199 at lib/refcount.c:28 refcount_warn_saturate+0xb5/0x170 Modules linked in: CPU: 26 UID: 0 PID: 3199 Comm: nfsd Not tainted 6.12.0-rc6-00079-g04ae226af01f-dirty #8 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 RIP: 0010:refcount_warn_saturate+0xb5/0x170 Code: cc cc 0f b6 1d b3 20 a5 03 80 fb 01 0f 87 65 48 d8 00 83 e3 01 75 e4 48 c7 c7 c0 3b 9b 85 c6 05 97 20 a5 03 01 e8 fb 3e 30 ff <0f> 0b eb cd 0f b6 1d 8a3 RSP: 0018:ffffc90008637cd8 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff83904fde RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff88871ed36380 RBP: ffff888158beeb40 R08: 0000000000000001 R09: fffff520010c6f56 R10: ffffc90008637ab7 R11: 0000000000000001 R12: 0000000000000001 R13: ffff888140e77400 R14: ffff888140e77408 R15: ffffffff858b42c0 FS: 0000000000000000(0000) GS:ffff88871ed00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000562384d32158 CR3: 000000055cc6a000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> ? refcount_warn_saturate+0xb5/0x170 ? __warn+0xa5/0x140 ? refcount_warn_saturate+0xb5/0x170 ? report_bug+0x1b1/0x1e0 ? handle_bug+0x53/0xa0 ? exc_invalid_op+0x17/0x40 ? asm_exc_invalid_op+0x1a/0x20 ? tick_nohz_tick_stopped+0x1e/0x40 ? refcount_warn_saturate+0xb5/0x170 ? refcount_warn_saturate+0xb5/0x170 nfs3svc_release_getacl+0xc9/0xe0 svc_process_common+0x5db/0xb60 ? __pfx_svc_process_common+0x10/0x10 ? __rcu_read_unlock+0x69/0xa0 ? __pfx_nfsd_dispatch+0x10/0x10 ? svc_xprt_received+0xa1/0x120 ? xdr_init_decode+0x11d/0x190 svc_process+0x2a7/0x330 svc_handle_xprt+0x69d/0x940 svc_recv+0x180/0x2d0 nfsd+0x168/0x200 ? __pfx_nfsd+0x10/0x10 kthread+0x1a2/0x1e0 ? kthread+0xf4/0x1e0 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x34/0x60 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK> Kernel panic - not syncing: kernel: panic_on_warn set ... Clear acl_access/acl_default after posix_acl_release is called to prevent UAF from being triggered.

References

URL	Tags
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/1fd94884174bd20beb1773990fd3b1aa877688d9	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/2e59b2b68782519560b3d6a41dd66a3d01a01cd3	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/55d947315fb5f67a35e4e1d3e01bb886b9c6decf	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/6f7cfee1a316891890c505563aa54f3476db52fd	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/7faf14a7b0366f153284db0ad3347c457ea70136	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/8a1737ae42c928384ab6447f6ee1a882510e85fa	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/f8d871523142f7895f250a856f8c4a4181614510	Patch
af854a3a-2127-422b-91ae-364da2661108	https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html
af854a3a-2127-422b-91ae-364da2661108	https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html
0b142b55-0307-4c5a-b3c9-f314f3fb7c5e	https://cert-portal.siemens.com/productcert/html/ssa-019113.html
0b142b55-0307-4c5a-b3c9-f314f3fb7c5e	https://cert-portal.siemens.com/productcert/html/ssa-082556.html
0b142b55-0307-4c5a-b3c9-f314f3fb7c5e	https://cert-portal.siemens.com/productcert/html/ssa-265688.html

Impacted products

Vendor	Product	Version
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	6.14
linux	linux_kernel	6.14

JSON

To clipboard

{
  "affected": [
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      "affectedData": [
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          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs2acl.c",
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        {
          "defaultStatus": "unknown",
          "product": "SIMATIC S7-1500 TM MFP - GNU/Linux subsystem",
          "vendor": "Siemens",
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        {
          "defaultStatus": "unknown",
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          "vendor": "Siemens",
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      "source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"
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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: clear acl_access/acl_default after releasing them\n\nIf getting acl_default fails, acl_access and acl_default will be released\nsimultaneously. However, acl_access will still retain a pointer pointing\nto the released posix_acl, which will trigger a WARNING in\nnfs3svc_release_getacl like this:\n\n------------[ cut here ]------------\nrefcount_t: underflow; use-after-free.\nWARNING: CPU: 26 PID: 3199 at lib/refcount.c:28\nrefcount_warn_saturate+0xb5/0x170\nModules linked in:\nCPU: 26 UID: 0 PID: 3199 Comm: nfsd Not tainted\n6.12.0-rc6-00079-g04ae226af01f-dirty #8\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS\n1.16.1-2.fc37 04/01/2014\nRIP: 0010:refcount_warn_saturate+0xb5/0x170\nCode: cc cc 0f b6 1d b3 20 a5 03 80 fb 01 0f 87 65 48 d8 00 83 e3 01 75\ne4 48 c7 c7 c0 3b 9b 85 c6 05 97 20 a5 03 01 e8 fb 3e 30 ff \u003c0f\u003e 0b eb\ncd 0f b6 1d 8a3\nRSP: 0018:ffffc90008637cd8 EFLAGS: 00010282\nRAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff83904fde\nRDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff88871ed36380\nRBP: ffff888158beeb40 R08: 0000000000000001 R09: fffff520010c6f56\nR10: ffffc90008637ab7 R11: 0000000000000001 R12: 0000000000000001\nR13: ffff888140e77400 R14: ffff888140e77408 R15: ffffffff858b42c0\nFS:  0000000000000000(0000) GS:ffff88871ed00000(0000)\nknlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000562384d32158 CR3: 000000055cc6a000 CR4: 00000000000006f0\nDR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\nCall Trace:\n \u003cTASK\u003e\n ? refcount_warn_saturate+0xb5/0x170\n ? __warn+0xa5/0x140\n ? refcount_warn_saturate+0xb5/0x170\n ? report_bug+0x1b1/0x1e0\n ? handle_bug+0x53/0xa0\n ? exc_invalid_op+0x17/0x40\n ? asm_exc_invalid_op+0x1a/0x20\n ? tick_nohz_tick_stopped+0x1e/0x40\n ? refcount_warn_saturate+0xb5/0x170\n ? refcount_warn_saturate+0xb5/0x170\n nfs3svc_release_getacl+0xc9/0xe0\n svc_process_common+0x5db/0xb60\n ? __pfx_svc_process_common+0x10/0x10\n ? __rcu_read_unlock+0x69/0xa0\n ? __pfx_nfsd_dispatch+0x10/0x10\n ? svc_xprt_received+0xa1/0x120\n ? xdr_init_decode+0x11d/0x190\n svc_process+0x2a7/0x330\n svc_handle_xprt+0x69d/0x940\n svc_recv+0x180/0x2d0\n nfsd+0x168/0x200\n ? __pfx_nfsd+0x10/0x10\n kthread+0x1a2/0x1e0\n ? kthread+0xf4/0x1e0\n ? __pfx_kthread+0x10/0x10\n ret_from_fork+0x34/0x60\n ? __pfx_kthread+0x10/0x10\n ret_from_fork_asm+0x1a/0x30\n \u003c/TASK\u003e\nKernel panic - not syncing: kernel: panic_on_warn set ...\n\nClear acl_access/acl_default after posix_acl_release is called to prevent\nUAF from being triggered."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: nfsd: borrar acl_access/acl_default despu\u00e9s de liberarlos Si la obtenci\u00f3n de acl_default falla, acl_access y acl_default se liberar\u00e1n simult\u00e1neamente. Sin embargo, acl_access a\u00fan conservar\u00e1 un puntero que apunta al posix_acl liberado, lo que activar\u00e1 una ADVERTENCIA en nfs3svc_release_getacl como esta: ------------[ cortar aqu\u00ed ]------------ refcount_t: desbordamiento insuficiente; use after free. ADVERTENCIA: CPU: 26 PID: 3199 at lib/refcount.c:28 refcount_warn_saturate+0xb5/0x170 Modules linked in: CPU: 26 UID: 0 PID: 3199 Comm: nfsd Not tainted 6.12.0-rc6-00079-g04ae226af01f-dirty #8 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 RIP: 0010:refcount_warn_saturate+0xb5/0x170 Code: cc cc 0f b6 1d b3 20 a5 03 80 fb 01 0f 87 65 48 d8 00 83 e3 01 75 e4 48 c7 c7 c0 3b 9b 85 c6 05 97 20 a5 03 01 e8 fb 3e 30 ff \u0026lt;0f\u0026gt; 0b eb cd 0f b6 1d 8a3 RSP: 0018:ffffc90008637cd8 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff83904fde RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff88871ed36380 RBP: ffff888158beeb40 R08: 0000000000000001 R09: fffff520010c6f56 R10: ffffc90008637ab7 R11: 0000000000000001 R12: 0000000000000001 R13: ffff888140e77400 R14: ffff888140e77408 R15: ffffffff858b42c0 FS: 0000000000000000(0000) GS:ffff88871ed00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000562384d32158 CR3: 000000055cc6a000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace:  ? refcount_warn_saturate+0xb5/0x170 ? __warn+0xa5/0x140 ? refcount_warn_saturate+0xb5/0x170 ? report_bug+0x1b1/0x1e0 ? handle_bug+0x53/0xa0 ? exc_invalid_op+0x17/0x40 ? asm_exc_invalid_op+0x1a/0x20 ? tick_nohz_tick_stopped+0x1e/0x40 ? refcount_warn_saturate+0xb5/0x170 ? refcount_warn_saturate+0xb5/0x170 nfs3svc_release_getacl+0xc9/0xe0 svc_process_common+0x5db/0xb60 ? __pfx_svc_process_common+0x10/0x10 ? __rcu_read_unlock+0x69/0xa0 ? __pfx_nfsd_dispatch+0x10/0x10 ? svc_xprt_received+0xa1/0x120 ? xdr_init_decode+0x11d/0x190 svc_process+0x2a7/0x330 svc_handle_xprt+0x69d/0x940 svc_recv+0x180/0x2d0 nfsd+0x168/0x200 ? __pfx_nfsd+0x10/0x10 kthread+0x1a2/0x1e0 ? kthread+0xf4/0x1e0 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x34/0x60 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30  Kernel panic - not syncing: kernel: panic_on_warn set ...  Borre acl_access/acl_default despu\u00e9s de llamar a posix_acl_release para evitar que se active UAF."
    }
  ],
  "id": "CVE-2025-21796",
  "lastModified": "2026-07-30T06:21:31.720",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      },
      {
        "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": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2025-21796",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2025-02-27T17:57:11.080279Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2025-02-27T03:15:20.497",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/1fd94884174bd20beb1773990fd3b1aa877688d9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
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      ],
      "url": "https://git.kernel.org/stable/c/2e59b2b68782519560b3d6a41dd66a3d01a01cd3"
    },
    {
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      "tags": [
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    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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    },
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
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      ],
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    },
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      "url": "https://git.kernel.org/stable/c/8a1737ae42c928384ab6447f6ee1a882510e85fa"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/f8d871523142f7895f250a856f8c4a4181614510"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html"
    },
    {
      "source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
      "url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
    },
    {
      "source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
      "url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html"
    },
    {
      "source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
      "url": "https://cert-portal.siemens.com/productcert/html/ssa-265688.html"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-416"
        }
      ],
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "type": "Secondary"
    }
  ]
}

CVE-2025-21796 (GCVE-0-2025-21796)

Vulnerability from cvelistv5 – Published: 2025-02-27 02:18 – Updated: 2026-09-08 08:40

Title

nfsd: clear acl_access/acl_default after releasing them

Summary

Severity

9.8 (Critical)


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

7.8 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2025-02-27 17:57 UTC

CWE

CWE-416 - Use After Free

Assigner

Linux CNA under the mitre root

CNA scorecard D 54/100 over 6618 records in the last 180 days details

References

12 references

URL	Tags
https://git.kernel.org/stable/c/8a1737ae42c928384…
https://git.kernel.org/stable/c/6f7cfee1a31689189…
https://git.kernel.org/stable/c/2e59b2b6878251956…
https://git.kernel.org/stable/c/55d947315fb5f67a3…
https://git.kernel.org/stable/c/f8d871523142f7895…
https://git.kernel.org/stable/c/1fd94884174bd20be…
https://git.kernel.org/stable/c/7faf14a7b0366f153…
https://lists.debian.org/debian-lts-announce/2025…
https://lists.debian.org/debian-lts-announce/2025…
https://cert-portal.siemens.com/productcert/html/…
https://cert-portal.siemens.com/productcert/html/…
https://cert-portal.siemens.com/productcert/html/…

Impacted products

9 products

Vendor	Product	Version
Linux	Linux	Affected: a257cdd0e2179630d3201c32ba14d7fcb3c3a055 , < 8a1737ae42c928384ab6447f6ee1a882510e85fa (git) Affected: a257cdd0e2179630d3201c32ba14d7fcb3c3a055 , < 6f7cfee1a316891890c505563aa54f3476db52fd (git) Affected: a257cdd0e2179630d3201c32ba14d7fcb3c3a055 , < 2e59b2b68782519560b3d6a41dd66a3d01a01cd3 (git) Affected: a257cdd0e2179630d3201c32ba14d7fcb3c3a055 , < 55d947315fb5f67a35e4e1d3e01bb886b9c6decf (git) Affected: a257cdd0e2179630d3201c32ba14d7fcb3c3a055 , < f8d871523142f7895f250a856f8c4a4181614510 (git) Affected: a257cdd0e2179630d3201c32ba14d7fcb3c3a055 , < 1fd94884174bd20beb1773990fd3b1aa877688d9 (git) Affected: a257cdd0e2179630d3201c32ba14d7fcb3c3a055 , < 7faf14a7b0366f153284db0ad3347c457ea70136 (git)
Linux	Linux	Affected: 2.6.13 Unaffected: 0 , < 2.6.13 (semver) Unaffected: 5.10.235 , ≤ 5.10.* (semver) Unaffected: 5.15.179 , ≤ 5.15.* (semver) Unaffected: 6.1.129 , ≤ 6.1.* (semver) Unaffected: 6.6.79 , ≤ 6.6.* (semver) Unaffected: 6.12.16 , ≤ 6.12.* (semver) Unaffected: 6.13.4 , ≤ 6.13.* (semver) Unaffected: 6.14 , ≤ * (original_commit_for_fix)
Siemens	SIMATIC S7-1500 CPU 1518-4 PN/DP MFP	Affected: V3.1.5 , < * (custom)
Siemens	SIMATIC S7-1500 CPU 1518-4 PN/DP MFP	Affected: V3.1.6 , < * (custom)
Siemens	SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP	Affected: V3.1.5 , < * (custom)
Siemens	SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP	Affected: V3.1.6 , < * (custom)
Siemens	SIMATIC S7-1500 TM MFP - GNU/Linux subsystem	Affected: 0 , < * (custom)
Siemens	SIPLUS S7-1500 CPU 1518-4 PN/DP MFP	Affected: V3.1.5 , < * (custom)
Siemens	SIPLUS S7-1500 CPU 1518-4 PN/DP MFP	Affected: V3.1.6 , < * (custom)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
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        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "LOCAL",
              "availabilityImpact": "HIGH",
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              "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"
            }
          },
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              "content": {
                "id": "CVE-2025-21796",
                "options": [
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                    "Exploitation": "none"
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                  },
                  {
                    "Technical Impact": "total"
                  }
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                "type": "CWE"
              }
            ]
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        ],
        "providerMetadata": {
          "dateUpdated": "2025-02-27T18:02:26.612Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      },
      {
        "providerMetadata": {
          "dateUpdated": "2025-11-03T20:59:40.254Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
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        },
        "references": [
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          },
          {
            "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html"
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        ],
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              }
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          },
          {
            "defaultStatus": "unknown",
            "product": "SIMATIC S7-1500 TM MFP - GNU/Linux subsystem",
            "vendor": "Siemens",
            "versions": [
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          },
          {
            "defaultStatus": "unknown",
            "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP",
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        "providerMetadata": {
          "dateUpdated": "2026-09-08T08:40:39.049Z",
          "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
          "shortName": "siemens-SADP"
        },
        "references": [
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          },
          {
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          },
          {
            "url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
          }
        ],
        "x_adpType": "supplier"
      }
    ],
    "cna": {
      "affected": [
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          "product": "Linux",
          "programFiles": [
            "fs/nfsd/nfs2acl.c",
            "fs/nfsd/nfs3acl.c"
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              "versionType": "git"
            },
            {
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            }
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        {
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          "programFiles": [
            "fs/nfsd/nfs2acl.c",
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          ],
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            },
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              "status": "unaffected",
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            },
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            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.79",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.16",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.13.*",
              "status": "unaffected",
              "version": "6.13.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.14",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.235",
                  "versionStartIncluding": "2.6.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.179",
                  "versionStartIncluding": "2.6.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.129",
                  "versionStartIncluding": "2.6.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.79",
                  "versionStartIncluding": "2.6.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.16",
                  "versionStartIncluding": "2.6.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.13.4",
                  "versionStartIncluding": "2.6.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.14",
                  "versionStartIncluding": "2.6.13",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: clear acl_access/acl_default after releasing them\n\nIf getting acl_default fails, acl_access and acl_default will be released\nsimultaneously. However, acl_access will still retain a pointer pointing\nto the released posix_acl, which will trigger a WARNING in\nnfs3svc_release_getacl like this:\n\n------------[ cut here ]------------\nrefcount_t: underflow; use-after-free.\nWARNING: CPU: 26 PID: 3199 at lib/refcount.c:28\nrefcount_warn_saturate+0xb5/0x170\nModules linked in:\nCPU: 26 UID: 0 PID: 3199 Comm: nfsd Not tainted\n6.12.0-rc6-00079-g04ae226af01f-dirty #8\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS\n1.16.1-2.fc37 04/01/2014\nRIP: 0010:refcount_warn_saturate+0xb5/0x170\nCode: cc cc 0f b6 1d b3 20 a5 03 80 fb 01 0f 87 65 48 d8 00 83 e3 01 75\ne4 48 c7 c7 c0 3b 9b 85 c6 05 97 20 a5 03 01 e8 fb 3e 30 ff \u003c0f\u003e 0b eb\ncd 0f b6 1d 8a3\nRSP: 0018:ffffc90008637cd8 EFLAGS: 00010282\nRAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff83904fde\nRDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff88871ed36380\nRBP: ffff888158beeb40 R08: 0000000000000001 R09: fffff520010c6f56\nR10: ffffc90008637ab7 R11: 0000000000000001 R12: 0000000000000001\nR13: ffff888140e77400 R14: ffff888140e77408 R15: ffffffff858b42c0\nFS:  0000000000000000(0000) GS:ffff88871ed00000(0000)\nknlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000562384d32158 CR3: 000000055cc6a000 CR4: 00000000000006f0\nDR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\nCall Trace:\n \u003cTASK\u003e\n ? refcount_warn_saturate+0xb5/0x170\n ? __warn+0xa5/0x140\n ? refcount_warn_saturate+0xb5/0x170\n ? report_bug+0x1b1/0x1e0\n ? handle_bug+0x53/0xa0\n ? exc_invalid_op+0x17/0x40\n ? asm_exc_invalid_op+0x1a/0x20\n ? tick_nohz_tick_stopped+0x1e/0x40\n ? refcount_warn_saturate+0xb5/0x170\n ? refcount_warn_saturate+0xb5/0x170\n nfs3svc_release_getacl+0xc9/0xe0\n svc_process_common+0x5db/0xb60\n ? __pfx_svc_process_common+0x10/0x10\n ? __rcu_read_unlock+0x69/0xa0\n ? __pfx_nfsd_dispatch+0x10/0x10\n ? svc_xprt_received+0xa1/0x120\n ? xdr_init_decode+0x11d/0x190\n svc_process+0x2a7/0x330\n svc_handle_xprt+0x69d/0x940\n svc_recv+0x180/0x2d0\n nfsd+0x168/0x200\n ? __pfx_nfsd+0x10/0x10\n kthread+0x1a2/0x1e0\n ? kthread+0xf4/0x1e0\n ? __pfx_kthread+0x10/0x10\n ret_from_fork+0x34/0x60\n ? __pfx_kthread+0x10/0x10\n ret_from_fork_asm+0x1a/0x30\n \u003c/TASK\u003e\nKernel panic - not syncing: kernel: panic_on_warn set ...\n\nClear acl_access/acl_default after posix_acl_release is called to prevent\nUAF from being triggered."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The vulnerable functions are the NFSACL sideband RPC handlers (program 100227, ACLPROC2/3_GETACL) served by the in-kernel nfsd on port 2049; a remote NFS client reaches them purely by sending a GETACL call with a filehandle and a mask.\nAC:L - The attacker fully controls the mask field that selects both the access and default ACL branches, and can retry indefinitely; the error condition is deterministic on FUSE-backed exports and on any file with a malformed/corrupt system.posix_acl_default xattr, and is otherwise reachable via the unlocked -ERANGE window in ext4_get_acl that the attacker drives from both sides with concurrent SETACL/GETACL.\nPR:N - NFS AUTH_SYS performs no real authentication \u2014 the client merely asserts a uid \u2014 and fh_verify() is called with NFSD_MAY_NOP, so nfsd_permission() returns 0 without any file ownership or mode check; any host permitted by the export list can issue GETACL against any object in the export.\nUI:N - The entire sequence is driven by attacker-sent RPC calls handled by the nfsd kernel threads; no action by a local user or administrator is required.\nS:U - The freed posix_acl, the dangling inode-\u003ei_acl, and the resulting corruption all reside in the kernel\u0027s own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - In the NFSv2-ACL encoder the released posix_acl is still passed to nfs_stream_encode_acl(), which reads a_count and up to 1024 a_entries[] from the freed slab object and transmits them to the remote client, yielding freed-heap disclosure plus a large out-of-bounds read; the cached-ACL variant additionally leaves inode-\u003ei_acl dangling for later reads.\nI:H - The second posix_acl_release() performs an atomic decrement into freed (potentially reallocated) slab memory, and in the cached case the dangling inode-\u003ei_acl leads to refcount_inc on freed memory, a genuine double free on the next set/forget_cached_acl, and posix_acl_permission() making file access-control decisions from attacker-groomable freed heap contents.\nA:H - The bug reproduces as a refcount_t underflow WARN in nfs3svc_release_getacl (kernel panic with panic_on_warn, as shown in the commit\u0027s own report), and the use-after-free of a slab object causes further corruption and oopses; it is remotely and repeatedly triggerable."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T11:54:31.388Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/8a1737ae42c928384ab6447f6ee1a882510e85fa"
        },
        {
          "url": "https://git.kernel.org/stable/c/6f7cfee1a316891890c505563aa54f3476db52fd"
        },
        {
          "url": "https://git.kernel.org/stable/c/2e59b2b68782519560b3d6a41dd66a3d01a01cd3"
        },
        {
          "url": "https://git.kernel.org/stable/c/55d947315fb5f67a35e4e1d3e01bb886b9c6decf"
        },
        {
          "url": "https://git.kernel.org/stable/c/f8d871523142f7895f250a856f8c4a4181614510"
        },
        {
          "url": "https://git.kernel.org/stable/c/1fd94884174bd20beb1773990fd3b1aa877688d9"
        },
        {
          "url": "https://git.kernel.org/stable/c/7faf14a7b0366f153284db0ad3347c457ea70136"
        }
      ],
      "title": "nfsd: clear acl_access/acl_default after releasing them",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-21796",
    "datePublished": "2025-02-27T02:18:32.191Z",
    "dateReserved": "2024-12-29T08:45:45.768Z",
    "dateUpdated": "2026-09-08T08:40:39.049Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

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Nomenclature

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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-2025-21796

CVE-2025-21796 (GCVE-0-2025-21796)

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