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CVE Record

CVE-2025-37823: net_sched: hfsc: Fix a potential UAF in hfsc_dequeue() too

In the Linux kernel, the following vulnerability has been resolved: net_sched: hfsc: Fix a potential UAF in hfsc_dequeue() too Similarly to the previous patch, we need to safe guard hfsc_dequeue() too. But for this one, we don't have a reliable reproducer.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2025-37823 is a potential use-after-free flaw in Linux’s HFSC network traffic scheduler. The supplied CVSS assessment indicates that a low-privileged local attacker could potentially compromise confidentiality, integrity, and availability. It is not described as remotely exploitable, and the kernel maintainers reported no reliable reproducer.

Executive priority

Treat as a high-priority kernel maintenance issue on systems with untrusted local users. Accelerate vendor-supported updates there; handle tightly controlled single-purpose systems through normal expedited patching. There is no supplied evidence of active exploitation or remote reachability, so emergency internet-wide incident response is not presently justified.

Technical view

The flaw affects hfsc_dequeue() in Linux network scheduling. Missing safeguarding may allow an object to be used after it is freed, creating possible memory corruption. CVSS 3.1 scores it 7.8 with local access, low complexity, low privileges, and no user interaction. Stable-kernel commits are provided for multiple maintained branches.

Likely exposure

Exposure is most relevant on affected Linux kernels where an attacker already has low-privileged local access and can reach the vulnerable HFSC path. Internet accessibility alone does not establish exposure. The supplied affected-version data spans several kernel branches but is insufficient for reliable distribution-package mapping; verify against each Linux vendor’s advisory.

Exploitation context

The supplied record is not in CISA KEV and provides no evidence of active exploitation. Kernel maintainers explicitly state they lacked a reliable reproducer. Exploitability should therefore be treated as plausible from the potential memory-safety condition and CVSS assessment, but not publicly demonstrated by this source bundle.

Researcher notes

The record identifies a potential UAF in hfsc_dequeue() and supplies eight stable-branch fixes, but no reliable reproducer or CWE. Its version presentation includes commit identifiers and broad kernel-version entries that may represent branch boundaries rather than distribution package versions. Use vendor backport status as the authoritative exposure test; do not infer vulnerability solely from the displayed upstream version.

Mitigation direction

  • Install the Linux distribution’s kernel update incorporating the applicable referenced stable fix.
  • Prioritize multi-user systems where untrusted users can obtain local accounts.
  • Reboot where required so the corrected kernel is actually running.
  • Consult the distribution vendor if its package-to-upstream-fix mapping is unclear.

Validation and detection

  • Inventory running kernel versions and distribution package revisions across Linux systems.
  • Compare each package against the applicable vendor advisory and referenced stable-kernel commit.
  • Confirm systems booted into the updated kernel after maintenance.
  • Assess whether HFSC scheduling is available or used and whether untrusted local access exists.
Prepared
Confidence
medium
Sources
12

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2025-37823 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
1ADP providers
11Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2025-37823Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2unaffected
LinuxLinux2.6.12, 0, 5.4.293, 5.10.237, 5.15.181, 6.1.136, 6.6.89, 6.12.26, 6.14.5, 6.15affected
Weakness

CWE details

No CWE listed

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