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CVE-2026-22999 (GCVE-0-2026-22999)

Vulnerability from cvelistv5 – Published: 2026-01-25 14:36 – Updated: 2026-08-05 12:20
VLAI
Title
net/sched: sch_qfq: do not free existing class in qfq_change_class()
Summary
In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_qfq: do not free existing class in qfq_change_class() Fixes qfq_change_class() error case. cl->qdisc and cl should only be freed if a new class and qdisc were allocated, or we risk various UAF.
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 2026-06-16 20:35 UTC
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 462dbc9101acd38e92eda93c0726857517a24bbd , < 2a64fb9b47afffeb5dbab5fd3a518e1436dcc90e (git)
Affected: 462dbc9101acd38e92eda93c0726857517a24bbd , < cff6cd703f41d8071995956142729e4bba160363 (git)
Affected: 462dbc9101acd38e92eda93c0726857517a24bbd , < f06f7635499bc806cbe2bbc8805c7cef8b1edddf (git)
Affected: 462dbc9101acd38e92eda93c0726857517a24bbd , < 0a234660dc70ce45d771cbc76b20d925b73ec160 (git)
Affected: 462dbc9101acd38e92eda93c0726857517a24bbd , < 362e269bb03f7076ba9990e518aeddb898232e50 (git)
Affected: 462dbc9101acd38e92eda93c0726857517a24bbd , < e9d8f11652fa08c647bf7bba7dd8163241a332cd (git)
Affected: 462dbc9101acd38e92eda93c0726857517a24bbd , < 3879cffd9d07aa0377c4b8835c4f64b4fb24ac78 (git)
guessed Create a notification for this product.
Linux Linux Affected: 3.8
Unaffected: 0 , < 3.8 (semver)
Unaffected: 5.10.249 , ≤ 5.10.* (semver)
Unaffected: 5.15.199 , ≤ 5.15.* (semver)
Unaffected: 6.1.162 , ≤ 6.1.* (semver)
Unaffected: 6.6.122 , ≤ 6.6.* (semver)
Unaffected: 6.12.67 , ≤ 6.12.* (semver)
Unaffected: 6.18.7 , ≤ 6.18.* (semver)
Unaffected: 6.19 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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                "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"
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          "ssvcV203": [
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              "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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                "options": [
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                  {
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                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-06-16T20:35:55.025194Z",
                "version": "2.0.3"
              }
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            "tags": [
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          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
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            "url": "https://git.kernel.org/stable/c/f06f7635499bc806cbe2bbc8805c7cef8b1edddf"
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Modified",
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                "value": "NVD-CWE-noinfo"
              }
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            "source": "nvd@nist.gov",
            "type": "Primary"
          }
        ]
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-05T13:41:23+00:00",
      "cve": "CVE-2026-22999",
      "id": "CVE-2026-22999",
      "initial_release_date": "2026-01-25T00:00:00+00:00",
      "product_status:known_affected": "90",
      "product_status:known_not_affected": "184",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: net/sched: sch_qfq: do not free existing class in qfq_change_class()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-22999.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-09-16T23:39:41Z",
      "cve": "CVE-2026-22999",
      "id": "CVE-2026-22999",
      "initial_release_date": "2026-01-26T00:24:47Z",
      "product_status:first_fixed": "2",
      "product_status:known_affected": "496",
      "product_status:known_not_affected": "4",
      "product_status:recommended": "745",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-22999",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-22999.json",
      "version": "50"
    },
    "vulnrichment": {
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                    "options": [
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                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "total"
                      }
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                    "role": "CISA Coordinator",
                    "timestamp": "2026-06-16T20:35:55.025194Z",
                    "version": "2.0.3"
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              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
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        ],
        "cna": {
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              "product": "Linux",
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                  "version": "6.19",
                  "versionType": "original_commit_for_fix"
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                  "value": "AV:L - The vulnerable `qfq_change_class()` path is reached through local rtnetlink/tc `RTM_NEWTCLASS` messages, ultimately sent via a netlink socket from userspace. It is not reachable directly from remote network packets.\nAC:L - The attacker controls the qdisc/class setup and can repeatedly attempt the class-change error path; there is no victim race or external timing requirement. Although the observed bad path depends on allocation failure, local memory pressure/failure conditions are attacker-influenceable, and uncertainty is scored upward.\nPR:L - Rtnetlink rejects non-GET tc operations without `CAP_NET_ADMIN` in the relevant network namespace. Because tc/qdisc operations are reachable inside user-created network namespaces on systems allowing unprivileged user namespaces, this is low privilege rather than real init-namespace root.\nUI:N - No victim action is required after the attacker has local execution and sends crafted netlink messages. The trigger is entirely attacker-driven.\nS:U - The impact is within the kernel/local host security authority. This is not a VM escape, IOMMU bypass, or cross-authority boundary violation.\nC:H - The bug frees an existing `struct qfq_class` while it remains reachable from the qdisc class hash and scheduler paths, creating a kernel heap use-after-free. Reclaiming the kmalloc-128 object can turn later class dumps/searches/pointer dereferences into strong information disclosure primitives.\nI:H - The stale class contains pointers such as `qdisc`, `agg`, list/hash nodes, and stats fields that are later read and modified by enqueue/dequeue, graft, dump, reset, and destroy paths. A controllable UAF in these scheduler structures is defensibly exploitable for kernel memory corruption or control-flow/data integrity compromise.\nA:H - The public syzbot report demonstrates a KASAN slab-use-after-free in `qfq_search_class`, and the stale object is also used by multiple qdisc paths. Even without full exploitation, this can cause kernel oops/panic or persistent scheduler corruption."
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}



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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.