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CVE-2026-53050
quota: Fix race of dquot_scan_active() with quota deactivation
Published 2026-06-24 (4 months ago) by the Linux kernel CNA. Subsystem fs/quota. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-53050 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixedDLA-4665-1 · 2026-07-03 · text | 6.1.176-1 | Update the kernel and reboot. DLA-4665-1 shipped the fix on 2026-07-03, in 6.1.176-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
dquot_scan_active() can race with quota deactivation in quota_release_workfn() like: CPU0 (quota_release_workfn) CPU1 (dquot_scan_active) ============================== ============================== spin_lock(&dq_list_lock); list_replace_init( &releasing_dquots, &rls_head); /* dquot X on rls_head, dq_count == 0, DQ_ACTIVE_B still set */ spin_unlock(&dq_list_lock); synchronize_srcu(&dquot_srcu); spin_lock(&dq_list_lock); list_for_each_entry(dquot, &inuse_list, dq_inuse) { /* finds dquot X */ dquot_active(X) -> true atomic_inc(&X->dq_count); } spin_unlock(&dq_list_lock); spin_lock(&dq_list_lock); dquot = list_first_entry(&rls_head); WARN_ON_ONCE(atomic_read(&dquot->dq_count)); The problem is not only a cosmetic one as under memory pressure the caller of dquot_scan_active() can end up working on freed dquot. Fix the problem by making sure the dquot is removed from releasing list when we acquire a reference to it.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
fs/quota/dquot.c
include/linux/quotaops.h
- What this is
- DISKQUOTAMAINTAINERS section matched on fs/quota/ · Maintained
Check it on the machine
grep -w CONFIG_QUOTA /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
Show whether Debian builds this, per release
Debian builds this code. Every release below compiles the affected file into the kernels it ships.
- bookworm, trixie, forky, sidy
- y
- built into the kernel image on every flavour - only a patch removes it
- Build switch
- CONFIG_QUOTA
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-06-24 (4 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.10%, higher than 1.0% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- fs/quota
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.10.199 | 5.10.258 | 2bdc80f46194 |
| 5.15.136 | 5.15.209 | f9438cb8c8ec |
| 6.1.59 | 6.1.175 | ac8a2e0d287e |
| 6.6 | 6.6.141 | 6678dde26570 |
| 6.6 | 6.12.91 | 61e25f664dc2 |
| 6.6 | 6.18.33 | fdd424d7c356 |
| 6.6 | 7.0.10 | 82cbdb4c1ebb |
| 6.6 | 7.1 | e93ab401da4b |
| 4.19.297 | 0 | 0 |
| 5.4.259 | 0 | 0 |
| 6.5.8 | 0 | 0 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4671-1 | 2026-07-05 | bullseye 6.1.176-1~deb11u1 | tracker |
| DLA-4665-1 | 2026-07-03 | bookworm 6.1.176-1 | tracker |
| DLA-4664-1 | 2026-07-03 | bullseye 5.10.259-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- The vulnerable path is reached through local filesystem quota activity on a mounted OCFS2 filesystem, via ordinary dquot lifetime changes racing with the OCFS2 quota sync worker. It is not reachable by remote packets or adjacent/physical input.
- AC:LAttack complexity, low
- This is a race, but a local attacker can repeatedly churn dquot references with filesystem operations while the periodic scanner runs. When uncertain, the higher-severity AC:L is appropriate.
- PR:LPrivileges required, low
- After OCFS2 quotas are enabled, an unprivileged local user with write access to the filesystem can trigger dquot allocation and release paths. Mounting/configuring quotas is an environmental prerequisite, not a privilege needed for each exploit attempt.
- UI:NUser interaction, none
- No victim interaction is required once the affected filesystem is mounted and quotas are active. The attacker can trigger the relevant filesystem operations directly.
- S:UScope, unchanged
- The impact remains within the kernel and the same host security authority. There is no VM escape, IOMMU bypass, or cross-authority boundary change.
- C:HConfidentiality impact, high
- The bug can lead to use-after-free of a dquot object under memory pressure. Kernel UAF conditions can be leveraged for memory disclosure, so confidentiality impact is High.
- I:HIntegrity impact, high
- The stale dquot/list state creates kernel heap use-after-free/list corruption, which can plausibly be shaped into write primitives or code execution. Integrity impact is therefore High.
- A:HAvailability impact, high
- The race already produces kernel WARN/oops-style failure conditions and can dereference freed kernel objects. This can crash or destabilize the kernel, so availability impact is High.