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NVD / CVE Program· CNA Linux

CVE-2025-21658: btrfs: avoid NULL pointer dereference if no valid extent tree

Noroxi assessment

Priority: Monitor (action score 22/100)

  • 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: 0.20% (FIRST EPSS).
  • 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.
  • Fixed version: Linux Linux 1fb37b7840fdcbf69d062a79d14afbf566b11873, 24b85a8b0310e0144da9ab30be42e87e6476638a, 6aecd91a5c5b68939cf4169e32bc49f3cd2dd329; azl3 kernel 6.6.64.2-9 on Azure Linux 3.0 6.6.76.1-1; azl3 kernel 6.6.76.1-1 on Azure Linux 3.0 6.6.76.1-1.

Low priority for now. Upgrade to Linux Linux 1fb37b7840fdcbf69d062a79d14afbf566b11873, 24b85a8b0310e0144da9ab30be42e87e6476638a, 6aecd91a5c5b68939cf4169e32bc49f3cd2dd329; azl3 kernel 6.6.64.2-9 on Azure Linux 3.0 6.6.76.1-1; azl3 kernel 6.6.76.1-1 on Azure Linux 3.0 6.6.76.1-1 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: avoid NULL pointer dereference if no valid extent tree [BUG] Syzbot reported a crash with the following call trace: BTRFS info (device loop0): scrub: started on devid 1 BUG: kernel NULL pointer dereference, address: 0000000000000208 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 106e70067 P4D 106e70067 PUD 107143067 PMD 0 Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 1 UID: 0 PID: 689 Comm: repro Kdump: loaded Tainted: G O 6.13.0-rc4-custom+ #206 Tainted: [O]=OOT_MODULE Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022 RIP: 0010:find_first_extent_item+0x26/0x1f0 [btrfs] Call Trace: <TASK> scrub_find_fill_first_stripe+0x13d/0x3b0 [btrfs] scrub_simple_mirror+0x175/0x260 [btrfs] scrub_stripe+0x5d4/0x6c0 [btrfs] scrub_chunk+0xbb/0x170 [btrfs] scrub_enumerate_chunks+0x2f4/0x5f0 [btrfs] btrfs_scrub_dev+0x240/0x600 [btrfs] btrfs_ioctl+0x1dc8/0x2fa0 [btrfs] ? do_sys_openat2+0xa5/0xf0 __x64_sys_ioctl+0x97/0xc0 do_syscall_64+0x4f/0x120 entry_SYSCALL_64_after_hwframe+0x76/0x7e </TASK> [CAUSE] The reproducer is using a corrupted image where extent tree root is corrupted, thus forcing to use "rescue=all,ro" mount option to mount the image. Then it triggered a scrub, but since scrub relies on extent tree to find where the data/metadata extents are, scrub_find_fill_first_stripe() relies on an non-empty extent root. But unfortunately scrub_find_fill_first_stripe() doesn't really expect an NULL pointer for extent root, it use extent_root to grab fs_info and triggered a NULL pointer dereference. [FIX] Add an extra check for a valid extent root at the beginning of scrub_find_fill_first_stripe(). The new error path is introduced by 42437a6386ff ("btrfs: introduce mount option rescue=ignorebadroots"), but that's pretty old, and later commit b979547513ff ("btrfs: scrub: introduce helper to find and fill sector info for a scrub_stripe") changed how we do scrub. So for kernels older than 6.6, the fix will need manual backport.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Jan 21, 2025
Updated
Oct 30, 2026
EPSS
0.2% · 10th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
5.5
CNA · Linux
5.5
agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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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.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel5.11 and later · before 6.6.72
  • linux linux kernel6.7 and later · before 6.12.10
  • linux linux kernel6.13

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

    • 5.11affected
    • 42437a6386ffeaaf200731e73d723ea491f3fe7d and later · before 1fb37b7840fdcbf69d062a79d14afbf566b11873affected · git
    • 42437a6386ffeaaf200731e73d723ea491f3fe7d and later · before 24b85a8b0310e0144da9ab30be42e87e6476638aaffected · git
    • 42437a6386ffeaaf200731e73d723ea491f3fe7d and later · before aee5f69f3e6cd82bfefaca1b70b40b6cd8f3f784affected · git
    • 42437a6386ffeaaf200731e73d723ea491f3fe7d and later · before 6aecd91a5c5b68939cf4169e32bc49f3cd2dd329affected · git
    • before 5.11not affected · semver
    • 6.1.191 and later · up to and including 6.1.*not affected · semver
    • 6.6.72 and later · up to and including 6.6.*not affected · semver
    • 6.12.10 and later · up to and including 6.12.*not affected · semver
    • 6.13 and laternot affected · original_commit_for_fix

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:13linuxbefore 6.12.10-16.12.10-1
openSUSE:Leap 15.6dtb-aarch64before 6.4.0-150600.23.60.36.4.0-150600.23.60.3
openSUSE:Leap 15.6kernel-64kbbefore 6.4.0-150600.23.60.46.4.0-150600.23.60.4
openSUSE:Leap 15.6kernel-azurebefore 6.4.0-150600.8.43.16.4.0-150600.8.43.1
openSUSE:Leap 15.6kernel-debugbefore 6.4.0-150600.23.60.46.4.0-150600.23.60.4
openSUSE:Leap 15.6kernel-defaultbefore 6.4.0-150600.23.60.56.4.0-150600.23.60.5
openSUSE:Leap 15.6kernel-default-basebefore 6.4.0-150600.23.60.5.150600.12.26.46.4.0-150600.23.60.5.150600.12.26.4
openSUSE:Leap 15.6kernel-docsbefore 6.4.0-150600.23.60.36.4.0-150600.23.60.3
openSUSE:Leap 15.6kernel-kvmsmallbefore 6.4.0-150600.23.60.46.4.0-150600.23.60.4
openSUSE:Leap 15.6kernel-obs-buildbefore 6.4.0-150600.23.60.36.4.0-150600.23.60.3
openSUSE:Leap 15.6kernel-obs-qabefore 6.4.0-150600.23.60.26.4.0-150600.23.60.2
openSUSE:Leap 15.6kernel-rtbefore 6.4.0-150600.10.44.16.4.0-150600.10.44.1
openSUSE:Leap 15.6kernel-rt_debugbefore 6.4.0-150600.10.44.16.4.0-150600.10.44.1
openSUSE:Leap 15.6kernel-sourcebefore 6.4.0-150600.23.60.46.4.0-150600.23.60.4
openSUSE:Leap 15.6kernel-source-azurebefore 6.4.0-150600.8.43.16.4.0-150600.8.43.1
openSUSE:Leap 15.6kernel-source-rtbefore 6.4.0-150600.10.44.16.4.0-150600.10.44.1
openSUSE:Leap 15.6kernel-symsbefore 6.4.0-150600.23.60.46.4.0-150600.23.60.4
openSUSE:Leap 15.6kernel-syms-azurebefore 6.4.0-150600.8.43.16.4.0-150600.8.43.1
openSUSE:Leap 15.6kernel-syms-rtbefore 6.4.0-150600.10.44.16.4.0-150600.10.44.1
openSUSE:Leap 15.6kernel-zfcpdumpbefore 6.4.0-150600.23.60.46.4.0-150600.23.60.4
SUSE:Linux Enterprise Live Patching 15 SP6kernel-livepatch-SLE15-SP6_Update_13before 1-150600.13.6.41-150600.13.6.4
SUSE:Linux Enterprise Live Patching 15 SP6kernel-livepatch-SLE15-SP6-RT_Update_13before 1-150600.1.5.11-150600.1.5.1
SUSE:Linux Enterprise Micro 5.3kernel-rtbefore 5.14.21-150400.15.145.15.14.21-150400.15.145.1

+22

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2024-57940Jan 21, 2025 · exfat: fix the infinite loop in exfat_readdir()
    22Monitor
  • ← EarlierCVE-2025-21656Jan 21, 2025 · hwmon: (drivetemp) Fix driver producing garbage data when SCSI errors occur
    22Monitor
  • Later →CVE-2025-21664Jan 21, 2025 · dm thin: make get_first_thin use rcu-safe list first function
    22Monitor

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 Linux1fb37b7840fdcbf69d062a79d14afbf566b11873Vendor (CNA)
Linux Linux24b85a8b0310e0144da9ab30be42e87e6476638aVendor (CNA)
Linux Linux6aecd91a5c5b68939cf4169e32bc49f3cd2dd329Vendor (CNA)
Linux Linuxaee5f69f3e6cd82bfefaca1b70b40b6cd8f3f784Vendor (CNA)
azl3 kernel 6.6.64.2-9 on Azure Linux 3.06.6.76.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 kernel 6.6.76.1-1 on Azure Linux 3.06.6.76.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.12.10-1 · Debian:13Package registry (OSV)
opensuse:dtb-aarch646.4.0-150600.23.60.3 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-64kb6.4.0-150600.23.60.4 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-azure6.4.0-150600.8.43.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-debug6.4.0-150600.23.60.4 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-default6.4.0-150600.23.60.5 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-default-base6.4.0-150600.23.60.5.150600.12.26.4 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-rt6.4.0-150600.10.44.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-rt_debug6.4.0-150600.10.44.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-source-azure6.4.0-150600.8.43.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-source-rt6.4.0-150600.10.44.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-syms-azure6.4.0-150600.8.43.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:kernel-syms-rt6.4.0-150600.10.44.1 · openSUSE:Leap 15.6Package registry (OSV)
suse:kernel-64kb6.4.0-150600.23.60.4 · SUSE:Linux Enterprise Module for Basesystem 15 SP6Package registry (OSV)
suse:kernel-azure6.4.0-150600.8.43.1 · SUSE:Linux Enterprise Module for Public Cloud 15 SP6Package registry (OSV)
suse:kernel-default6.4.0-150600.23.60.5 · SUSE:Linux Enterprise Module for Basesystem 15 SP6Package registry (OSV)
suse:kernel-default-base6.4.0-150600.23.60.5.150600.12.26.4 · SUSE:Linux Enterprise Module for Basesystem 15 SP6Package registry (OSV)
suse:kernel-livepatch-SLE15-SP6-RT_Update_131-150600.1.5.1 · SUSE:Linux Enterprise Live Patching 15 SP6Package registry (OSV)
suse:kernel-rt6.4.0-150600.10.44.1 · SUSE:Real Time Module 15 SP6Package registry (OSV)
suse:kernel-rt_debug6.4.0-150600.10.44.1 · SUSE:Real Time Module 15 SP6Package registry (OSV)
suse:kernel-source6.4.0-150600.23.60.4 · SUSE:Linux Enterprise Module for Basesystem 15 SP6Package registry (OSV)
suse:kernel-source-azure6.4.0-150600.8.43.1 · SUSE:Linux Enterprise Module for Public Cloud 15 SP6Package registry (OSV)
suse:kernel-source-rt6.4.0-150600.10.44.1 · SUSE:Real Time Module 15 SP6Package registry (OSV)
suse:kernel-syms-azure6.4.0-150600.8.43.1 · SUSE:Linux Enterprise Module for Public Cloud 15 SP6Package registry (OSV)

+1

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.

No history yet (it accumulates with the daily EPSS job).

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).

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
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-476 · NULL Pointer Dereference

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

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✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (3 more)

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

All records