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NVD / CVE Program· CNA Linux

CVE-2026-64593: btrfs: do not trim a device which is not writeable

Noroxi assessment

Priority: Monitor (action score 0/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.16% (FIRST EPSS).
  • Fixed version: Linux Linux 02c903fc6fc7e16c5d1f22d18784f1208acf43e3, 1b1937eb08f51319bf71575484cde2b8c517aedc, 210af872eafa0cf572a84cb303c0f9d2914c1226; azl3 kernel 6.6.143.1-1 on Azure Linux 3.0 6.6.150.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 02c903fc6fc7e16c5d1f22d18784f1208acf43e3, 1b1937eb08f51319bf71575484cde2b8c517aedc, 210af872eafa0cf572a84cb303c0f9d2914c1226; azl3 kernel 6.6.143.1-1 on Azure Linux 3.0 6.6.150.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: btrfs: do not trim a device which is not writeable [BUG] There is a bug report that btrfs/242 can randomly fail with the following NULL pointer dereference: run fstests btrfs/242 at 2026-06-01 10:25:08 BTRFS: device fsid d4d7f234-487c-4787-88e4-47a8b68c9874 devid 1 transid 9 /dev/sdc (8:32) scanned by mount (122609) BTRFS info (device sdc): first mount of filesystem d4d7f234-487c-4787-88e4-47a8b68c9874 BTRFS info (device sdc): using crc32c checksum algorithm BTRFS warning (device sdc): devid 2 uuid fbe72d72-3272-482d-80fb-ab88ed398192 is missing BTRFS warning (device sdc): devid 2 uuid fbe72d72-3272-482d-80fb-ab88ed398192 is missing BTRFS info (device sdc): allowing degraded mounts BTRFS info (device sdc): turning on async discard BTRFS info (device sdc): enabling free space tree Unable to handle kernel NULL pointer dereference at virtual address 0000000000000018 user pgtable: 4k pages, 48-bit VAs, pgdp=000000013fd6b000 CPU: 4 UID: 0 PID: 122625 Comm: fstrim Not tainted 7.0.10-2-default #1 PREEMPT(full) openSUSE Tumbleweed e9a5f6b24978fba3bf015a992f865837fdfff3dd Hardware name: QEMU KVM Virtual Machine, BIOS edk2-20250812-19.fc42 08/12/2025 pstate: 01400005 (nzcv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) pc : btrfs_trim_fs+0x34c/0xa00 [btrfs] lr : btrfs_trim_fs+0x1f0/0xa00 [btrfs] Call trace: btrfs_trim_fs+0x34c/0xa00 [btrfs f02c1d570ceea621c69d302ba75dd61868083840] (P) btrfs_ioctl_fitrim+0xe8/0x178 [btrfs f02c1d570ceea621c69d302ba75dd61868083840] btrfs_ioctl+0xdd4/0x2bd8 [btrfs f02c1d570ceea621c69d302ba75dd61868083840] __arm64_sys_ioctl+0xac/0x108 invoke_syscall.constprop.0+0x5c/0xd0 el0_svc_common.constprop.0+0x40/0xf0 do_el0_svc+0x24/0x40 el0_svc+0x40/0x1d0 el0t_64_sync_handler+0xa0/0xe8 el0t_64_sync+0x1b0/0x1b8 Code: 17ffff83 f94017e0 f9002be0 f9402ea0 (f9400c00) ---[ end trace 0000000000000000 ]--- Also the reporter is very kind to test the following ASSERT() added to btrfs_trim_free_extents_throttle(): ASSERT(device->bdev, "devid=%llu path=%s dev_state=0x%lx\n", device->devid, btrfs_dev_name(device), device->dev_state); And it shows the following output: assertion failed: device->bdev, in extent-tree.c:6630 (devid=2 path=/dev/sdd dev_state=0x82) Which means the device->bdev is NULL, and the dev_state is BTRFS_DEV_STATE_IN_FS_METADATA | BTRFS_DEV_STATE_ITEM_FOUND, without BTRFS_DEV_STATE_WRITEABLE flag set. [CAUSE] The pc points to the following call chain: btrfs_trim_fs() |- btrfs_trim_free_extents() |- btrfs_trim_free_extents_throttle() |- bdev_max_discard_sectors(device->bdev) So the NULL pointer dereference is caused by device->bdev being NULL. This looks impossible by a quick glance, as just before calling btrfs_trim_free_extents_throttle(), we have skipped any device that has BTRFS_DEV_STATE_MISSING flag set. However in this particular case, there is a window where the missing device is later re-scanned, causing btrfs to remove the BTRFS_DEV_STATE_MISSING flag: btrfs_control_ioctl() |- btrfs_scan_one_device() |- device_list_add() |- rcu_assign_pointer(device->name, name); | This updates the missing device's path to the new good path. | |- clear_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state) This removes the BTRFS_DEV_STATE_MISSING flag. This allows the missing device to re-appear and clear the BTRFS_DEV_STATE_MISSING flag. However the device still does not have the BTRFS_DEV_STATE_WRITEABLE flag set, nor is its bdev pointer updated. The bdev pointer remains NULL, triggering the crash later. [FIX] This is a big de-synchronization between BTRFS_DEV_STATE_MISSING and device->bdev pointer, and shows a gap in btrfs's re-appearing-device handling. The proper handling of re-appearing device will need quite some extra work, which is out of the context of this small ---truncated---

—No exploit Fix available
Published
Aug 6, 2026
Updated
Aug 17, 2026
EPSS
0.1% · 5th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

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

    • 4.3affected
    • 499f377f49f085ee4aa214c738e948e88626f39b and later · before f41ae7e6664f3c4361129728f2c4d5f3ed995251affected · git
    • 499f377f49f085ee4aa214c738e948e88626f39b and later · before 210af872eafa0cf572a84cb303c0f9d2914c1226affected · git
    • 499f377f49f085ee4aa214c738e948e88626f39b and later · before 3d8fa4b828a86b33c60858e58aaab6df273ede05affected · git
    • 499f377f49f085ee4aa214c738e948e88626f39b and later · before 9c894159c5b8adc84072e3af0e55b0473a69564eaffected · git
    • 499f377f49f085ee4aa214c738e948e88626f39b and later · before 02c903fc6fc7e16c5d1f22d18784f1208acf43e3affected · git
    • 499f377f49f085ee4aa214c738e948e88626f39b and later · before 7a64521802997257b144e6edfb4e278dbeb972ddaffected · git
    • 499f377f49f085ee4aa214c738e948e88626f39b and later · before b4af31b898a948e29861cb0bae734058f9a49d9baffected · git
    • 499f377f49f085ee4aa214c738e948e88626f39b and later · before 1b1937eb08f51319bf71575484cde2b8c517aedcaffected · git
    • before 4.3not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.180-16.1.180-1
Debian:12linux-6.12before 6.12.100-1~deb12u16.12.100-1~deb12u1
Debian:13linuxbefore 6.12.96-16.12.96-1
Debian:14linuxbefore 7.1.4-17.1.4-1
SUSE:Linux Enterprise Live Patching 12 SP5kernel-defaultbefore 4.12.14-122.336.14.12.14-122.336.1
SUSE:Linux Enterprise Live Patching 12 SP5kgraft-patch-SLE12-SP5_Update_89before 1-8.3.11-8.3.1
SUSE:Linux Enterprise Server 12 SP5-LTSSkernel-sourcebefore 4.12.14-122.336.14.12.14-122.336.1
SUSE:Linux Enterprise Server 12 SP5-LTSSkernel-symsbefore 4.12.14-122.336.14.12.14-122.336.1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-64591Aug 6, 2026 · iommu/vt-d: Avoid WARNING in sva unbind path
    0Monitor
  • ← EarlierCVE-2026-64592Aug 6, 2026 · riscv: mm: Unconditionally sfence.vma for spurious fault
    0Monitor
  • Later →CVE-2026-64594Aug 6, 2026 · usb: gadget: f_fs: initialize reset_work at allocation time
    0Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux02c903fc6fc7e16c5d1f22d18784f1208acf43e3Vendor (CNA)
Linux Linux1b1937eb08f51319bf71575484cde2b8c517aedcVendor (CNA)
Linux Linux210af872eafa0cf572a84cb303c0f9d2914c1226Vendor (CNA)
Linux Linux3d8fa4b828a86b33c60858e58aaab6df273ede05Vendor (CNA)
Linux Linux7a64521802997257b144e6edfb4e278dbeb972ddVendor (CNA)
Linux Linux9c894159c5b8adc84072e3af0e55b0473a69564eVendor (CNA)
Linux Linuxb4af31b898a948e29861cb0bae734058f9a49d9bVendor (CNA)
Linux Linuxf41ae7e6664f3c4361129728f2c4d5f3ed995251Vendor (CNA)
azl3 kernel 6.6.143.1-1 on Azure Linux 3.06.6.150.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.180-1 · Debian:12Package registry (OSV)
debian:linux-6.126.12.100-1~deb12u1 · Debian:12Package registry (OSV)
suse:kernel-default4.12.14-122.336.1 · SUSE:Linux Enterprise Live Patching 12 SP5Package registry (OSV)
suse:kernel-source4.12.14-122.336.1 · SUSE:Linux Enterprise Server 12 SP5-LTSSPackage registry (OSV)
suse:kernel-syms4.12.14-122.336.1 · SUSE:Linux Enterprise Server 12 SP5-LTSSPackage registry (OSV)
suse:kgraft-patch-SLE12-SP5_Update_891-8.3.1 · SUSE:Linux Enterprise Live Patching 12 SP5Package 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.

EPSS, last 120 days

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 researchers

Finders, 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.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

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

  1. Fix✗ → ✓

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References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records