Vulnerability-Lookup

FKIE_CVE-2025-37890

Vulnerability from fkie_nvd - Published: 2025-05-16 13:15 - Updated: 2026-07-30 06:22

Severity

7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/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: net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc As described in Gerrard's report [1], we have a UAF case when an hfsc class has a netem child qdisc. The crux of the issue is that hfsc is assuming that checking for cl->qdisc->q.qlen == 0 guarantees that it hasn't inserted the class in the vttree or eltree (which is not true for the netem duplicate case). This patch checks the n_active class variable to make sure that the code won't insert the class in the vttree or eltree twice, catering for the reentrant case. [1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/

References

URL	Tags
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/141d34391abbb315d68556b7c67ad97885407547	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/273bbcfa53541cde38b2003ad88a59b770306421	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/2e7093c7a8aba5d4f8809f271488e5babe75e202	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/6082a87af4c52f58150d40dec1716011d871ac21	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/8df7d37d626430035b413b97cee18396b3450bef	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/ac39fd4a757584d78ed062d4f6fd913f83bd98b5	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/e0cf8ee23e1915431f262a7b2dee0c7a7d699af0	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/e3e949a39a91d1f829a4890e7dfe9417ac72e4d0	Patch
af854a3a-2127-422b-91ae-364da2661108	https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html	Mailing List
af854a3a-2127-422b-91ae-364da2661108	https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html	Mailing List

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	*
linux	linux_kernel	5.0
linux	linux_kernel	5.0
linux	linux_kernel	5.0
linux	linux_kernel	5.0
linux	linux_kernel	5.0
linux	linux_kernel	5.0
linux	linux_kernel	5.0
linux	linux_kernel	6.15
linux	linux_kernel	6.15
linux	linux_kernel	6.15
linux	linux_kernel	6.15
debian	debian_linux	11.0

JSON

To clipboard

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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc\n\nAs described in Gerrard\u0027s report [1], we have a UAF case when an hfsc class\nhas a netem child qdisc. The crux of the issue is that hfsc is assuming\nthat checking for cl-\u003eqdisc-\u003eq.qlen == 0 guarantees that it hasn\u0027t inserted\nthe class in the vttree or eltree (which is not true for the netem\nduplicate case).\n\nThis patch checks the n_active class variable to make sure that the code\nwon\u0027t insert the class in the vttree or eltree twice, catering for the\nreentrant case.\n\n[1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/"
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: net_sched: hfsc: corrige una vulnerabilidad UAF en la clase con netem como qdisc hijo Como se describe en el informe de Gerrard [1], tenemos un caso UAF cuando una clase hfsc tiene una qdisc hijo netem. El quid de la cuesti\u00f3n es que hfsc asume que la comprobaci\u00f3n de cl-\u0026gt;qdisc-\u0026gt;q.qlen == 0 garantiza que no ha insertado la clase en vttree o eltree (lo que no es cierto para el caso de duplicado de netem). Este parche comprueba la variable de clase n_active para asegurarse de que el c\u00f3digo no inserte la clase en vttree o eltree dos veces, atendiendo al caso reentrante. [1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/"
    }
  ],
  "id": "CVE-2025-37890",
  "lastModified": "2026-07-30T06:22:28.833",
  "metrics": {
    "cvssMetricV31": [
      {
        "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"
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        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      },
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        "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": "nvd@nist.gov",
        "type": "Primary"
      }
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    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2025-37890",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-06-10T20:42:08.844756Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2025-05-16T13:15:52.437",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
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    },
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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      "url": "https://git.kernel.org/stable/c/273bbcfa53541cde38b2003ad88a59b770306421"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
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    },
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      "source": "af854a3a-2127-422b-91ae-364da2661108",
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  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Modified",
  "weaknesses": [
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      "source": "nvd@nist.gov",
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}

CVE-2025-37890 (GCVE-0-2025-37890)

Vulnerability from cvelistv5 – Published: 2025-05-16 13:01 – Updated: 2026-08-05 11:58

Title

net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc

Summary

Severity

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 2026-06-10 20:42 UTC

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 6653 records in the last 180 days details

References

10 references

URL	Tags
https://git.kernel.org/stable/c/273bbcfa53541cde3…
https://git.kernel.org/stable/c/e0cf8ee23e1915431…
https://git.kernel.org/stable/c/e3e949a39a91d1f82…
https://git.kernel.org/stable/c/8df7d37d626430035…
https://git.kernel.org/stable/c/6082a87af4c52f581…
https://git.kernel.org/stable/c/2e7093c7a8aba5d4f…
https://git.kernel.org/stable/c/ac39fd4a757584d78…
https://git.kernel.org/stable/c/141d34391abbb315d…
https://lists.debian.org/debian-lts-announce/2025…
https://lists.debian.org/debian-lts-announce/2025…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea , < 273bbcfa53541cde38b2003ad88a59b770306421 (git) Affected: 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea , < e0cf8ee23e1915431f262a7b2dee0c7a7d699af0 (git) Affected: 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea , < e3e949a39a91d1f829a4890e7dfe9417ac72e4d0 (git) Affected: 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea , < 8df7d37d626430035b413b97cee18396b3450bef (git) Affected: 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea , < 6082a87af4c52f58150d40dec1716011d871ac21 (git) Affected: 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea , < 2e7093c7a8aba5d4f8809f271488e5babe75e202 (git) Affected: 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea , < ac39fd4a757584d78ed062d4f6fd913f83bd98b5 (git) Affected: 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea , < 141d34391abbb315d68556b7c67ad97885407547 (git)
Linux	Linux	Affected: 5.0 Unaffected: 0 , < 5.0 (semver) Unaffected: 5.4.294 , ≤ 5.4.* (semver) Unaffected: 5.10.238 , ≤ 5.10.* (semver) Unaffected: 5.15.182 , ≤ 5.15.* (semver) Unaffected: 6.1.138 , ≤ 6.1.* (semver) Unaffected: 6.6.90 , ≤ 6.6.* (semver) Unaffected: 6.12.28 , ≤ 6.12.* (semver) Unaffected: 6.14.6 , ≤ 6.14.* (semver) Unaffected: 6.15 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2025-11-03T19:57:02.260Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html"
          },
          {
            "url": "https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html"
          }
        ],
        "title": "CVE Program Container"
      },
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2025-37890",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-06-10T20:42:08.844756Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-06-11T18:44:19.853Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sched/sch_hfsc.c"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
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              "versionType": "git"
            },
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              "lessThan": "e0cf8ee23e1915431f262a7b2dee0c7a7d699af0",
              "status": "affected",
              "version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea",
              "versionType": "git"
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              "versionType": "git"
            },
            {
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              "status": "affected",
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              "versionType": "git"
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            },
            {
              "lessThan": "141d34391abbb315d68556b7c67ad97885407547",
              "status": "affected",
              "version": "37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea",
              "versionType": "git"
            }
          ]
        },
        {
          "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": "5.0"
            },
            {
              "lessThan": "5.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.4.*",
              "status": "unaffected",
              "version": "5.4.294",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.238",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.182",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.138",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.90",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.28",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.14.*",
              "status": "unaffected",
              "version": "6.14.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.15",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.4.294",
                  "versionStartIncluding": "5.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.238",
                  "versionStartIncluding": "5.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.138",
                  "versionStartIncluding": "5.0",
                  "vulnerable": true
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.90",
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc\n\nAs described in Gerrard\u0027s report [1], we have a UAF case when an hfsc class\nhas a netem child qdisc. The crux of the issue is that hfsc is assuming\nthat checking for cl-\u003eqdisc-\u003eq.qlen == 0 guarantees that it hasn\u0027t inserted\nthe class in the vttree or eltree (which is not true for the netem\nduplicate case).\n\nThis patch checks the n_active class variable to make sure that the code\nwon\u0027t insert the class in the vttree or eltree twice, catering for the\nreentrant case.\n\n[1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/"
        }
      ],
      "metrics": [
        {
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - Exploitation requires configuring an hfsc qdisc with a netem child (duplicate enabled) via RTNETLINK/tc and then transmitting packets locally, so the attacker must have local access to the system. Per kernel scoring guidance, tc/netlink qdisc bugs are Local.\nAC:L - The reentrancy is deterministic \u2014 netem\u0027s duplicate path re-enters hfsc_enqueue() synchronously on the same CPU before the child qdisc\u0027s qlen is incremented, so a single packet with duplicate=100% reliably double-activates the class. No race or uncontrolled memory-layout condition is involved.\nPR:L - Qdisc/class creation requires CAP_NET_ADMIN, but only ns_capable() over the netns owner user namespace (netlink_net_capable in rtnetlink_rcv_msg), which any unprivileged user obtains with `unshare -Urn` on default distro configs. Triggering enqueue only needs sending a packet over the local device.\nUI:N - The attacker performs every step \u2014 qdisc/class setup, packet transmission, and class deletion \u2014 with no action from any other user or administrator.\nS:U - The corruption and its consequences are confined to the kernel\u0027s own memory and scheduling structures within the same security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The freed hfsc_class remains linked in the parent\u0027s vt_tree/cf_tree and the eligible rbtree, so subsequent rbtree traversals read attacker-groomed heap contents; a UAF of a slab object with reclaimed contents yields a kernel information-disclosure primitive.\nI:H - Stale rb_node links cause rb_insert_color()/rb_erase()/vttree_update() to write into freed memory that the attacker can reclaim with a controlled object, giving a write primitive suitable for control-flow hijacking and privilege escalation. The doubly-inserted el_node additionally corrupts the eligible rbtree structure itself.\nA:H - Even without weaponization, the use-after-free and corrupted rbtree produce oopses, hangs on cyclic tree traversal, or a kernel panic, taking the whole system down."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T11:58:05.817Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/273bbcfa53541cde38b2003ad88a59b770306421"
        },
        {
          "url": "https://git.kernel.org/stable/c/e0cf8ee23e1915431f262a7b2dee0c7a7d699af0"
        },
        {
          "url": "https://git.kernel.org/stable/c/e3e949a39a91d1f829a4890e7dfe9417ac72e4d0"
        },
        {
          "url": "https://git.kernel.org/stable/c/8df7d37d626430035b413b97cee18396b3450bef"
        },
        {
          "url": "https://git.kernel.org/stable/c/6082a87af4c52f58150d40dec1716011d871ac21"
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        {
          "url": "https://git.kernel.org/stable/c/2e7093c7a8aba5d4f8809f271488e5babe75e202"
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        {
          "url": "https://git.kernel.org/stable/c/ac39fd4a757584d78ed062d4f6fd913f83bd98b5"
        },
        {
          "url": "https://git.kernel.org/stable/c/141d34391abbb315d68556b7c67ad97885407547"
        }
      ],
      "title": "net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2025-37890",
    "datePublished": "2025-05-16T13:01:12.798Z",
    "dateReserved": "2025-04-16T04:51:23.963Z",
    "dateUpdated": "2026-08-05T11:58:05.817Z",
    "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.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

Order JSON

How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Publication & reservation Sightings KEV catalogs Other timestamps

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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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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.

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