fs/resctrl: Fix use-after-free during unmount
In the Linux kernel, the following vulnerability has been resolved: fs/resctrl: Fix use-after-free during unmount During unmount or failure teardown all mon_data structures that contain monitoring event file private data are freed after which kernfs nodes are removed. However, the RDT_DELETED flag is never set for the statically allocated default resource group. A concurrent reader of an event file associated with the default resource group may, after dropping kernfs active protection, block on rdtgroup_mutex while unmount proceeds to free the file private data and destroy the kernfs node without waiting for the reader. When the mutex is released, the reader wakes up, observes that RDT_DELETED is not set for the default group, and dereferences the already-freed file private data. The scenario can be depicted as follows: CPU0 CPU1 /* * Default resource group's * monitoring data accessible via * kernfs file with kernfs_node::priv * pointing to a struct mon_data. * User opens the file for reading. */ rdtgroup_mondata_show() /* arch encounters fatal error */ rdtgroup_kn_lock_live() resctrl_exit() atomic_inc(&rdtgroup_default.waitcount) cpus_read_lock() kernfs_break_active_protection(kn) mutex_lock(&rdtgroup_mutex) cpus_read_lock() resctrl_fs_teardown() mutex_lock(&rdtgroup_mutex) rmdir_all_sub() mon_put_kn_priv() /* Delete all mon_data structures */ rdtgroup_destroy_root() kernfs_destroy_root() rdtgroup_default.kn = NULL mutex_unlock(&rdtgroup_mutex) /* * rdtgroup_default.flags is empty so * rdtgroup_kn_lock_live() returns * &rdtgroup_default */ md = of->kn->priv; /* md points to freed mon_data */ Set RDT_DELETED for the default group unconditionally since the flag does not lead to the freeing of this statically allocated group. Do not allow a new resctrl mount if there are any waiters on default group of previous mount. A new mount will re-initialize the default group that would appear to waiters from previous mount as though the default group is accessible causing them to access the mon_data structures from the previous mount that have been removed.
- Published
- Aug 15, 2026
- Updated
- Aug 17, 2026
- EPSS
- 0.2% · 6th percentile
- CWE
- —
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Report tools
Action score
31
Monitor
Low priority for now.
- CVSS
- 31 / 40 · 7.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.2%
CNA vs NVD score
- NVD
- —
- CNA · Linux
- 7.8
- NVD has not scored this yet; the score shown is the CNA’s.
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpAffected systems
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Versions reported by the vendor
Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.
Linux Linux
- 6.16affected
- 2a65660385444e9d9deffe995c71ee20443ef76e and later · before 7b7bb07efe41bb646a93c4624aa2bb35df190342affected · git
- 2a65660385444e9d9deffe995c71ee20443ef76e and later · before 7d330a1d663381579b9d5dafa642b1b3158a0ce2affected · git
- 2a65660385444e9d9deffe995c71ee20443ef76e and later · before 52fce648607e0d6a76eeb443d78708c49df1c554affected · git
- before 6.16not affected · semver
- 6.18.42 and later · up to and including 6.18.*not affected · semver
- 7.1.5 and later · up to and including 7.1.*not affected · semver
- 7.2 and laternot affected · original_commit_for_fix
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:14 | linux | before 7.1.5-1 | 7.1.5-1 |
Same product
linux: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation40Plan
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- CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()40Plan
- CVE-2026-74309vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler40Plan
- CVE-2026-74280crypto: marvell/octeontx - fix DMA cleanup using wrong loop index40Plan
- CVE-2026-74279crypto: cavium/cpt - fix DMA cleanup using wrong loop index40Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Linux Linux | 52fce648607e0d6a76eeb443d78708c49df1c554 | Vendor (CNA) |
| Linux Linux | 7b7bb07efe41bb646a93c4624aa2bb35df190342 | Vendor (CNA) |
| Linux Linux | 7d330a1d663381579b9d5dafa642b1b3158a0ce2 | Vendor (CNA) |
| debian:linux | 7.1.5-1 · Debian:14 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
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Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Someone with local access to the system can trigger it.
- A low-privileged account is enough.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
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CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- git.kernel.org/stable/c/52fce648607e0d6a76eeb443d78708c49df1c554
- git.kernel.org/stable/c/7b7bb07efe41bb646a93c4624aa2bb35df190342
- git.kernel.org/stable/c/7d330a1d663381579b9d5dafa642b1b3158a0ce2
Vendor advisories and official records. Exploit/PoC links are deliberately left out.