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NVD / CVE Program· CNA Linux

CVE-2024-26726: btrfs: don't drop extent_map for free space inode on write error

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: 0.25% (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 02f2b95b00bf57d20320ee168b30fb7f3db8e555, 143842584c1237ebc248b2547c29d16bbe400a92, 5571e41ec6e56e35f34ae9f5b3a335ef510e0ade.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 02f2b95b00bf57d20320ee168b30fb7f3db8e555, 143842584c1237ebc248b2547c29d16bbe400a92, 5571e41ec6e56e35f34ae9f5b3a335ef510e0ade 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: don't drop extent_map for free space inode on write error While running the CI for an unrelated change I hit the following panic with generic/648 on btrfs_holes_spacecache. assertion failed: block_start != EXTENT_MAP_HOLE, in fs/btrfs/extent_io.c:1385 ------------[ cut here ]------------ kernel BUG at fs/btrfs/extent_io.c:1385! invalid opcode: 0000 [#1] PREEMPT SMP NOPTI CPU: 1 PID: 2695096 Comm: fsstress Kdump: loaded Tainted: G W 6.8.0-rc2+ #1 RIP: 0010:__extent_writepage_io.constprop.0+0x4c1/0x5c0 Call Trace: <TASK> extent_write_cache_pages+0x2ac/0x8f0 extent_writepages+0x87/0x110 do_writepages+0xd5/0x1f0 filemap_fdatawrite_wbc+0x63/0x90 __filemap_fdatawrite_range+0x5c/0x80 btrfs_fdatawrite_range+0x1f/0x50 btrfs_write_out_cache+0x507/0x560 btrfs_write_dirty_block_groups+0x32a/0x420 commit_cowonly_roots+0x21b/0x290 btrfs_commit_transaction+0x813/0x1360 btrfs_sync_file+0x51a/0x640 __x64_sys_fdatasync+0x52/0x90 do_syscall_64+0x9c/0x190 entry_SYSCALL_64_after_hwframe+0x6e/0x76 This happens because we fail to write out the free space cache in one instance, come back around and attempt to write it again. However on the second pass through we go to call btrfs_get_extent() on the inode to get the extent mapping. Because this is a new block group, and with the free space inode we always search the commit root to avoid deadlocking with the tree, we find nothing and return a EXTENT_MAP_HOLE for the requested range. This happens because the first time we try to write the space cache out we hit an error, and on an error we drop the extent mapping. This is normal for normal files, but the free space cache inode is special. We always expect the extent map to be correct. Thus the second time through we end up with a bogus extent map. Since we're deprecating this feature, the most straightforward way to fix this is to simply skip dropping the extent map range for this failed range. I shortened the test by using error injection to stress the area to make it easier to reproduce. With this patch in place we no longer panic with my error injection test.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Apr 3, 2024
Updated
Jun 17, 2026
EPSS
0.2% · 17th 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.

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

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2024-26726

When you'll hear from us

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  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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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 kernelbefore 6.1.79
  • linux linux kernel6.2 and later · before 6.6.18
  • linux linux kernel6.7 and later · before 6.7.6
  • linux linux kernel6.8

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

    • 3.12affected
    • 77cef2ec5484564eca6bd12a2b4a1e88fd766fbc and later · before 143842584c1237ebc248b2547c29d16bbe400a92affected · git
    • 77cef2ec5484564eca6bd12a2b4a1e88fd766fbc and later · before 02f2b95b00bf57d20320ee168b30fb7f3db8e555affected · git
    • 77cef2ec5484564eca6bd12a2b4a1e88fd766fbc and later · before 7bddf18f474f166c19f91b2baf67bf7c5eda03f7affected · git
    • 77cef2ec5484564eca6bd12a2b4a1e88fd766fbc and later · before a4b7741c8302e28073bfc6dd1c2e73598e5e535eaffected · git
    • 77cef2ec5484564eca6bd12a2b4a1e88fd766fbc and later · before 5571e41ec6e56e35f34ae9f5b3a335ef510e0adeaffected · git
    • before 3.12not affected · semver
    • 5.15.187 and later · up to and including 5.15.*not affected · semver
    • 6.1.79 and later · up to and including 6.1.*not affected · semver
    • 6.6.18 and later · up to and including 6.6.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.82-16.1.82-1
Debian:13linuxbefore 6.7.7-16.7.7-1

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-2024-26724Apr 3, 2024 · net/mlx5: DPLL, Fix possible use after free after delayed work timer triggers
    31Monitor
  • ← EarlierCVE-2024-26725Apr 3, 2024 · dpll: fix possible deadlock during netlink dump operation
    22Monitor
  • Later →CVE-2024-26727Apr 3, 2024 · btrfs: do not ASSERT() if the newly created subvolume already got read
    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 Linux02f2b95b00bf57d20320ee168b30fb7f3db8e555Vendor (CNA)
Linux Linux143842584c1237ebc248b2547c29d16bbe400a92Vendor (CNA)
Linux Linux5571e41ec6e56e35f34ae9f5b3a335ef510e0adeVendor (CNA)
Linux Linux7bddf18f474f166c19f91b2baf67bf7c5eda03f7Vendor (CNA)
Linux Linuxa4b7741c8302e28073bfc6dd1c2e73598e5e535eVendor (CNA)
debian:linux6.1.82-1 · Debian:12Package 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.

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.

  • CVE-2023-2156330 days apartA flaw was found in the networking subsystem of the Linux kernel within the handling of the RPL protocol.
    32Monitor
  • CVE-2023-526218 days apartbpf: Check rcu_read_lock_trace_held() before calling bpf map helpers
    31Monitor
  • CVE-2025-39803530 days apartscsi: ufs: core: Remove WARN_ON_ONCE() call from ufshcd_uic_cmd_compl()
    31Monitor
  • CVE-2024-267270 days apartbtrfs: do not ASSERT() if the newly created subvolume already got read
    22Monitor
  • CVE-2022-4863325 days apartdrm/gma500: Fix WARN_ON(lock->magic != lock) error
    22Monitor
  • CVE-2024-2694628 days apartkprobes/x86: Use copy_from_kernel_nofault() to read from unsafe address
    22Monitor

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

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-617 · Reachable Assertion

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 (4 more)

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

All records