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Linux Kernel btrfs EUVDEUVD-2026-32218

| CVE-2026-45934 MEDIUM
2026-05-27 416baaa9-dc9f-4396-8d5f-8c081fb06d67 GHSA-62rp-r79h-7q8x
Information Disclosure Linux
5.5
CVSS 3.1 · NVD
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Recon
    Obtain local low-privilege shell
  2. Delivery
    Write data to exhaust btrfs block group
  3. Exploit
    Trigger DUP chunk allocation
  4. Install
    Allocator produces overlapping physical stripe ranges
  5. C2
    insert_dev_extents() returns EEXIST (-17)
  6. Execute
    btrfs transaction abort
  7. Impact
    Filesystem enters error state

Vulnerability Assessment

Exploitation Conditions

Exploitation requires a local user account with low privileges (PR:L per CVSS - root is not required) on a Linux system where btrfs is the active filesystem configured with DUP chunk profiles (the default for single-device btrfs metadata). The defect fires during chunk allocation events triggered by either writing data that exhausts an existing block group under normal filesystem pressure, or explicitly via the CONFIG_BTRFS_EXPERIMENTAL forced chunk allocation sysfs interface (/sys/fs/btrfs/.../force_chunk_alloc). Limiting factors: the attack vector is strictly local (AV:L) - remote exploitation is not possible without prior local code execution; systems using non-DUP chunk profiles or multi-device RAID configurations are not described as affected; and the trigger is non-deterministic under normal write workloads, requiring specific allocation boundary conditions. The 'Information Disclosure' tag in the source intelligence does not reflect any actual data exposure condition described in this CVE.
Impact

The NVD CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H, score 5.5) accurately characterizes this as a local, low-complexity, low-privilege denial-of-service with no data exposure. The EPSS score of 0.02% (4th percentile) corroborates negligible exploitation interest, consistent with its nature as a filesystem reliability defect rather than a remotely exploitable flaw. The vulnerability is absent from CISA KEV, and no POC exploit code has been identified. Notably, the 'Information Disclosure' tag in the intelligence metadata conflicts with the CVSS C:N metric and the CVE description - no confidentiality impact is described or plausible; this tag appears to be a mislabeling and should not influence risk triage. Real-world risk is bounded to btrfs-dependent production workloads: a transaction abort can render the filesystem unavailable, with potential for data inconsistency if crash recovery is incomplete. Systems using btrfs as the root or primary data filesystem with DUP metadata are most exposed. This is a medium-priority patch target for btrfs operators, not a general security emergency.
Exploit ScenarioDerived

A local user with a standard unprivileged account on a Linux server using btrfs with DUP metadata writes data until the current block group is exhausted, forcing a new chunk allocation. The kernel's chunk allocator generates non-consecutive physical address gaps between DUP stripes, causing insert_dev_extents() to return EEXIST, aborting the btrfs transaction and leaving the filesystem in an error state requiring manual recovery. No exploit code has been identified; this scenario describes the natural trigger conditions of an observed reliability defect.
This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Jun 24, 2026

Btrfs transaction aborts in the Linux kernel allow local low-privileged users to crash the filesystem by triggering a logic defect in DUP chunk allocation that generates overlapping physical address ranges in the chunk map. Systems running btrfs with DUP metadata profiles - the default for single-device btrfs deployments - can encounter EEXIST (-17) errors in insert_dev_extents() during btrfs_create_pending_block_groups(), causing the transaction to abort and the filesystem to enter an error state. No public exploit or active exploitation (CISA KEV) has been identified; with an EPSS of 0.02% (4th percentile), this is a kernel reliability defect of operational concern to btrfs operators rather than a traditional attack vector.

RemediationAI

Upgrade to Linux kernel 6.19.4 or 6.18.14, which contain the verified upstream fix for this btrfs chunk allocation defect, as confirmed by EUVD-2026-32218. Distribution users should apply vendor-provided stable kernel updates incorporating the three fix commits referenced above. For systems that cannot immediately upgrade, disabling CONFIG_BTRFS_EXPERIMENTAL removes the forced chunk allocation sysfs trigger but does not fully eliminate exposure, as DUP allocation can still be triggered under normal write pressure; the trade-off is reduced ergonomics for btrfs experimental features. Converting btrfs metadata from DUP to SINGLE profile via btrfs balance is a more aggressive workaround that removes the precondition but sacrifices redundancy and requires sufficient free space. Any system that has already experienced this transaction abort should run btrfs check --readonly on the affected device before remounting to assess filesystem integrity prior to returning the volume to service.

Affected VersionsENISA

Linux patch: 6.19.4
Linux 1b9845081633072c18f30d8cfd09c267adf0b109 <b14c5e04bd0f722ed631845599d52d03fcae1bc1
Linux patch: 0
Linux patch: 7.0
Linux patch: 6.18.14
Linux 1b9845081633072c18f30d8cfd09c267adf0b109 <156cac365e27a82b64ae510c5f463fd81f0265b1
Linux 4.1
Linux 1b9845081633072c18f30d8cfd09c267adf0b109 <7d4eadee7042d27fcea659fcdd738f463a7d2e70

Affected Packages

euvd linux no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

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Technical ContextAI · show details

The vulnerability resides in the Linux kernel btrfs subsystem within fs/btrfs/block-group.c. When btrfs allocates DUP chunks - a mode that writes two copies of data on a single block device - the chunk allocator can produce non-consecutive physical address gaps between the two stripes. The stack trace demonstrates that stripe 1 of one chunk and stripe 0 of a second chunk are assigned overlapping physical address ranges (e.g., both mapped to 0x0000000142500000-0x0000000182500000). When insert_dev_extents() subsequently attempts to register these extents, it encounters an already-occupied slot, returns EEXIST (-17), and triggers a btrfs transaction abort at block-group.c:2876. The CPE data identifies affected products as linux_kernel from version 4.1 (including release candidates rc2 through rc8) across multiple stable branches. No CWE is formally assigned, but the root cause is a bookkeeping ordering defect in chunk map state management during DUP allocation - not a memory safety or privilege escalation issue. The bug is reliably triggered via CONFIG_BTRFS_EXPERIMENTAL's forced chunk allocation sysfs interface but can theoretically occur during any DUP chunk allocation under normal filesystem pressure.

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Severity by source

NVD PRIMARY 5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
vuln.today AI 5.5 MEDIUM

Local low-privilege trigger causing filesystem abort; no confidentiality or integrity impact; AC:L because no special preconditions beyond a btrfs DUP mount.

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.0 AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE 4.7 MEDIUM
AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Red Hat 7.0 MEDIUM

Primary rating from NVD.

CVSS VectorNVD

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

4
CVSS changed
Jun 24, 2026 - 17:22 NVD
5.5 (MEDIUM)
Patch available
May 27, 2026 - 19:46 EUVD
CVE Published
May 27, 2026 - 14:17 nvd
MEDIUM 5.5
CVE Published
May 27, 2026 - 14:17 nvd
UNKNOWN (no severity yet)

DescriptionNVD

In the Linux kernel, the following vulnerability has been resolved:

btrfs: fix EEXIST abort due to non-consecutive gaps in chunk allocation

I have been observing a number of systems aborting at insert_dev_extents() in btrfs_create_pending_block_groups(). The following is a sample stack trace of such an abort coming from forced chunk allocation (typically behind CONFIG_BTRFS_EXPERIMENTAL) but this can theoretically happen to any DUP chunk allocation.

[81.801] ------------[ cut here ]------------ [81.801] BTRFS: Transaction aborted (error -17) [81.801] WARNING: fs/btrfs/block-group.c:2876 at btrfs_create_pending_block_groups+0x721/0x770 [btrfs], CPU#1: bash/319 [81.802] Modules linked in: virtio_net btrfs xor zstd_compress raid6_pq null_blk [81.803] CPU: 1 UID: 0 PID: 319 Comm: bash Kdump: loaded Not tainted 6.19.0-rc6+ #319 NONE [81.803] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.17.0-2-2 04/01/2014 [81.804] RIP: 0010:btrfs_create_pending_block_groups+0x723/0x770 [btrfs] [81.806] RSP: 0018:ffffa36241a6bce8 EFLAGS: 00010282 [81.806] RAX: 000000000000000d RBX: ffff8e699921e400 RCX: 0000000000000000 [81.807] RDX: 0000000002040001 RSI: 00000000ffffffef RDI: ffffffffc0608bf0 [81.807] RBP: 00000000ffffffef R08: ffff8e69830f6000 R09: 0000000000000007 [81.808] R10: ffff8e699921e5e8 R11: 0000000000000000 R12: ffff8e6999228000 [81.808] R13: ffff8e6984d82000 R14: ffff8e69966a69c0 R15: ffff8e69aa47b000 [81.809] FS: 00007fec6bdd9740(0000) GS:ffff8e6b1b379000(0000) knlGS:0000000000000000 [81.809] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [81.810] CR2: 00005604833670f0 CR3: 0000000116679000 CR4: 00000000000006f0 [81.810] Call Trace: [81.810] <TASK> [81.810] __btrfs_end_transaction+0x3e/0x2b0 [btrfs] [81.811] btrfs_force_chunk_alloc_store+0xcd/0x140 [btrfs] [81.811] kernfs_fop_write_iter+0x15f/0x240 [81.812] vfs_write+0x264/0x500 [81.812] ksys_write+0x6c/0xe0 [81.812] do_syscall_64+0x66/0x770 [81.812] entry_SYSCALL_64_after_hwframe+0x76/0x7e [81.813] RIP: 0033:0x7fec6be66197 [81.814] RSP: 002b:00007fffb159dd30 EFLAGS: 00000202 ORIG_RAX: 0000000000000001 [81.815] RAX: ffffffffffffffda RBX: 00007fec6bdd9740 RCX: 00007fec6be66197 [81.815] RDX: 0000000000000002 RSI: 0000560483374f80 RDI: 0000000000000001 [81.816] RBP: 0000560483374f80 R08: 0000000000000000 R09: 0000000000000000 [81.816] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000002 [81.817] R13: 00007fec6bfb85c0 R14: 00007fec6bfb5ee0 R15: 00005604833729c0 [81.817] </TASK> [81.817] irq event stamp: 20039 [81.818] hardirqs last enabled at (20047): [<ffffffff99a68302>] __up_console_sem+0x52/0x60 [81.818] hardirqs last disabled at (20056): [<ffffffff99a682e7>] __up_console_sem+0x37/0x60 [81.819] softirqs last enabled at (19470): [<ffffffff999d2b46>] __irq_exit_rcu+0x96/0xc0 [81.819] softirqs last disabled at (19463): [<ffffffff999d2b46>] __irq_exit_rcu+0x96/0xc0 [81.820] ---[ end trace 0000000000000000 ]--- [81.820] BTRFS: error (device dm-7 state A) in btrfs_create_pending_block_groups:2876: errno=-17 Object already exists

Inspecting these aborts with drgn, I observed a pattern of overlapping chunk_maps. Note how stripe 1 of the first chunk overlaps in physical address with stripe 0 of the second chunk.

Physical Start Physical End Length Logical Type Stripe ---------------------------------------------------------------------------------------------------- 0x0000000102500000 0x0000000142500000 1.0G 0x0000000641d00000 META|DUP 0/2 0x0000000142500000 0x0000000182500000 1.0G 0x0000000641d00000 META|DUP 1/2 0x0000000142500000 0x0000000182500000 1.0G 0x0000000601d00000 META|DUP 0/2 0x0000000182500000 0x00000001c2500000 1.0G 0x0000000601d00000 META|DUP 1/2

Now how could this possibly happen? All chunk allocation is ---truncated---

Threat Intelligence Overview

EPSS Score
0.0%
Top 96% exploitable
Prevalence
Medium
btrfs default on Fedora and openSUSE but not universally deployed
Data Quality
6 sources
Confidence: High
EUVD NVD CVE.org EPSS MSRC Vendor VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.0%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Defer
Exploitation· derived
None
System Exposure· derived
Small
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

28
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +28
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Same technique Information Disclosure

View all
CVE-2019-2725 CRITICAL POC
9.8
CVE-2021-34523 CRITICAL POC
9.0
CVE-2013-2251 CRITICAL POC
9.8
CVE-2017-5638 CRITICAL POC
9.8
CVE-2025-24813 CRITICAL POC
9.8
CVE-2025-68613 HIGH POC
8.8
CVE-2015-1701 HIGH POC
7.8
CVE-2017-0147 HIGH POC
7.5

Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Affected
SUSE Linux Enterprise High Performance Computing 15 SP7 Affected

References

Advisories & patches
ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-45934 ADVISORY https://vuldb.com/vuln/366270 REF https://git.kernel.org/stable/c/09207c3975e1f8f76a52472004dfcab997b4cbd6 REF https://git.kernel.org/stable/c/12addb8ab5eec94098d4c7c6614830ccbe7ad130 REF https://git.kernel.org/stable/c/156cac365e27a82b64ae510c5f463fd81f0265b1 REF https://git.kernel.org/stable/c/7d4eadee7042d27fcea659fcdd738f463a7d2e70 REF https://git.kernel.org/stable/c/8f01e82c58f40739dfec32fc83dfd66711d473b9 REF https://git.kernel.org/stable/c/b14c5e04bd0f722ed631845599d52d03fcae1bc1

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