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CVE Record

CVE-2025-39717: open_tree_attr: do not allow id-mapping changes without OPEN_TREE_CLONE

In the Linux kernel, the following vulnerability has been resolved: open_tree_attr: do not allow id-mapping changes without OPEN_TREE_CLONE As described in commit 7a54947e727b ('Merge patch series "fs: allow changing idmappings"'), open_tree_attr(2) was necessary in order to allow for a detached mount to be created and have its idmappings changed without the risk of any racing threads operating on it. For this reason, mount_setattr(2) still does not allow for id-mappings to be changed. However, there was a bug in commit 2462651ffa76 ("fs: allow changing idmappings") which allowed users to bypass this restriction by calling open_tree_attr(2) *without* OPEN_TREE_CLONE. can_idmap_mount() prevented this bug from allowing an attached mountpoint's id-mapping from being modified (thanks to an is_anon_ns() check), but this still allows for detached (but visible) mounts to have their be id-mapping changed. This risks the same UAF and locking issues as described in the merge commit, and was likely unintentional.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A Linux kernel mount-management flaw could let a low-privileged local user change identity mappings on certain detached but visible mounts. This may trigger use-after-free or locking failures, potentially compromising confidentiality, integrity, and availability. Exploitation requires local access; the supplied evidence does not establish remote or active exploitation.

Executive priority

Treat as a high-priority kernel update for exposed multi-user or untrusted-workload systems. It is not evidenced as remotely or actively exploited, so prioritize according to local-access exposure. Require asset owners to confirm vendor applicability, deploy the corrected kernel, reboot, and document the running version.

Technical view

The kernel incorrectly permitted open_tree_attr(2) without OPEN_TREE_CLONE to alter mount identity mappings. Although can_idmap_mount() protects attached mountpoints, detached but visible mounts remained exposed to unsafe concurrent operations. The record assigns CVSS 3.1 score 7.8: local, low-complexity exploitation with low privileges, no user interaction, and potentially high impact.

Likely exposure

Exposure is limited to Linux systems running versions identified as affected by the supplied CVE record and allowing an untrusted local user or workload to reach the relevant mount operations. The supplied version data is ambiguous, listing 6.15, 6.16.4, and 6.17 without clear range semantics; confirm status through your distribution or kernel vendor.

Exploitation context

The supplied record marks this CVE as absent from KEV and provides no evidence of exploitation in the wild. The CVSS vector indicates a local, low-privilege attack with low complexity and no user interaction. The source bundle does not establish practical exploit reliability, required capabilities, or container-specific reachability.

Researcher notes

The safety boundary requires identity-mapping changes to operate on a cloned, detached mount, preventing concurrent access during mutation. The faulty path bypassed OPEN_TREE_CLONE, leaving detached but visible mounts susceptible to use-after-free and locking problems. The supplied record provides fix commits but insufficient detail to determine exact stable-version boundaries or exploitability prerequisites.

Mitigation direction

  • Install a vendor-supported kernel containing the referenced upstream fixes.
  • Confirm affected and fixed releases with your Linux distribution or kernel vendor.
  • Prioritize multi-user hosts and systems running untrusted local workloads.
  • Restrict unnecessary local access while patching is pending.
  • Reboot into the updated kernel after installation, following vendor guidance.

Validation and detection

  • Record the running kernel version on every potentially exposed host.
  • Compare each kernel build against authoritative distribution security guidance.
  • Verify the installed kernel incorporates one of the referenced fixes.
  • Confirm systems rebooted into the corrected kernel, not merely installed it.
  • Review local-user and untrusted-workload access on unpatched systems.
Prepared
Confidence
high
Sources
4

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.

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CVE-2025-39717 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
0ADP providers
3Source 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-2025-39717Attack 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.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux2462651ffa76b87f9c2e4403ef6e6b89b703fb2f, 2462651ffa76b87f9c2e4403ef6e6b89b703fb2funaffected
LinuxLinux6.15, 0, 6.16.4, 6.17affected
Weakness

CWE details

No CWE listed

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