Linux KernelOperating system · Linux
CVE-2026-53126
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn the Linux kernel, the following vulnerability has been resolved: blk-cgroup: fix disk reference leak in blkcg_maybe_throttle_current() Add the missing put_disk() on the error path in blkcg_maybe_throttle_current(). When blkcg lookup, blkg lookup, or blkg_tryget() fails, the function jumps to the out label which only calls rcu_read_unlock() but does not release the disk reference acquired by blkcg_schedule_throttle() via get_device(). Since current->throttle_disk is already set to NULL before the lookup, blkcg_exit() cannot release this reference either, causing the disk to never be freed. Restore the reference release that was present as blk_put_queue() in the original code but was inadvertently dropped during the conversion from request_queue to gendisk.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceA disk reference leak exists in blkcg_maybe_throttle_current() in the Linux kernel's blk-cgroup subsystem. When blkcg lookup, blkg lookup, or blkg_tryget() fails, the function jumps to the 'out' label which only calls rcu_read_unlock() but fails to release a disk reference acquired earlier by blkcg_schedule_throttle() via get_device(). Since current->throttle_disk is set to NULL before the lookup, blkcg_exit() cannot release this reference either, causing a permanent resource leak.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Linux KernelOperating system
>= 6.3, < 6.6.141>= 6.7, < 6.12.91>= 6.13, < 6.18.33>= 6.19, < 7.0.10CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check kernel version against affected rangesRun `uname -r` or `cat /proc/version` and compare the version to: >= 6.3, < 6.6.141; >= 6.7, < 6.12.91; >= 6.13, < 6.18.33; >= 6.19, < 7.0.10Affected if The kernel version falls within any of the affected ranges listed
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Verify blk-cgroup kernel configuration is enabledCheck if the kernel has blk-cgroup support by running `zcat /proc/config.gz 2>/dev/null | grep -i CONFIG_BLK_CGROUP` or checking `/boot/config-$(uname -r)`Affected if CONFIG_BLK_CGROUP=y or CONFIG_BLK_CGROUP_IOPOLL=y is set (the vulnerability code path exists in the kernel)
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Confirm blk-cgroup throttling is actively usedLook for processes with a non-NULL throttle_disk field: `grep -r throttle_disk /proc/*/stack 2>/dev/null | head -5` or check cgroup blkio controller usage with `cat /sys/fs/cgroup/blkio/*/throttle.read_iops_device 2>/dev/null`Affected if The system is actively using blk-cgroup throttling (the code path that calls blkcg_schedule_throttle() is being executed)
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Detect leaked disk references in kernelMonitor for leaked block device references: check `ls -la /sys/block/*/holders` and compare reference counts, or use `cat /proc/diskstats` to look for unusual disk countsAffected if There are block devices with unexpectedly high reference counts that do not correlate with active mounts or open handles
You are affected if your kernel version is in the affected range AND blk-cgroup is enabled AND the system is actively using blk-cgroup throttling features.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped6.6.1416.12.916.18.33
Apply the kernel patch that adds the missing put_disk() call on the error path in blkcg_maybe_throttle_current() to restore proper disk reference release that was inadvertently dropped during the request_queue to gendisk conversion.
Upgrade to kernel 6.6.141+, 6.12.91+, 6.18.33+, or 7.0.10+ depending on your current branch
- Identify the affected kernel version by running: uname -r
- Apply the kernel patch that adds the missing put_disk() call on the error path in blkcg_maybe_throttle_current() in block/blk-cgroup.c
- The patch adds: put_disk(current->throttle_disk); current->throttle_disk = NULL; before the rcu_read_unlock() call on the error path
- Rebuild the kernel with the applied patch
- Reboot the system with the patched kernel
- Verify the fix is present by checking the source code in block/blk-cgroup.c for the put_disk() call in blkcg_maybe_throttle_current()
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Linux Kernel
Scoped from the published advisory
- Consultation1.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-53126 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-53126 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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