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NVD / CVE Program· CNA Linux

CVE-2026-45920: ext4: fix dirtyclusters double decrement on fs shutdown

Noroxi assessment

Priority: Monitor (action score 31/100)

  • 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: 0.14% (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 3924aea2c33df3864929c1acd178bfc29d8f005f, 523d5a4df3c649fa305c89efb552ec62a1ce9d3d, 55576fa14771d33994c29a9ae960e07bb3f56c20.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 3924aea2c33df3864929c1acd178bfc29d8f005f, 523d5a4df3c649fa305c89efb552ec62a1ce9d3d, 55576fa14771d33994c29a9ae960e07bb3f56c20 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: ext4: fix dirtyclusters double decrement on fs shutdown fstests test generic/388 occasionally reproduces a warning in ext4_put_super() associated with the dirty clusters count: WARNING: CPU: 7 PID: 76064 at fs/ext4/super.c:1324 ext4_put_super+0x48c/0x590 [ext4] Tracing the failure shows that the warning fires due to an s_dirtyclusters_counter value of -1. IOW, this appears to be a spurious decrement as opposed to some sort of leak. Further tracing of the dirty cluster count deltas and an LLM scan of the resulting output identified the cause as a double decrement in the error path between ext4_mb_mark_diskspace_used() and the caller ext4_mb_new_blocks(). First, note that generic/388 is a shutdown vs. fsstress test and so produces a random set of operations and shutdown injections. In the problematic case, the shutdown triggers an error return from the ext4_handle_dirty_metadata() call(s) made from ext4_mb_mark_context(). The changed value is non-zero at this point, so ext4_mb_mark_diskspace_used() does not exit after the error bubbles up from ext4_mb_mark_context(). Instead, the former decrements both cluster counters and returns the error up to ext4_mb_new_blocks(). The latter falls into the !ar->len out path which decrements the dirty clusters counter a second time, creating the inconsistency. To avoid this problem and simplify ownership of the cluster reservation in this codepath, lift the counter reduction to a single place in the caller. This makes it more clear that ext4_mb_new_blocks() is responsible for acquiring cluster reservation (via ext4_claim_free_clusters()) in the !delalloc case as well as releasing it, regardless of whether it ends up consumed or returned due to failure.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
May 27, 2026
Updated
Jun 24, 2026
EPSS
0.1% · 3th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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.

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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 kernel2.6.29 and later · before 5.10.253
  • linux linux kernel5.11 and later · before 5.15.203
  • linux linux kernel5.16 and later · before 6.1.167
  • linux linux kernel6.2 and later · before 6.6.130
  • linux linux kernel6.7 and later · before 6.12.75
  • linux linux kernel6.13 and later · before 6.18.14
  • linux linux kernel6.19 and later · before 6.19.4

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

    • 2.6.29affected
    • 0087d9fb3f29f59e8d42c8b058376d80e5adde4c and later · before 523d5a4df3c649fa305c89efb552ec62a1ce9d3daffected · git
    • 0087d9fb3f29f59e8d42c8b058376d80e5adde4c and later · before ca408af08544d96769c93a3d81a7f63f61129e95affected · git
    • 0087d9fb3f29f59e8d42c8b058376d80e5adde4c and later · before 55576fa14771d33994c29a9ae960e07bb3f56c20affected · git
    • 0087d9fb3f29f59e8d42c8b058376d80e5adde4c and later · before dbc4e10619ed87a50e637b96f2e574df36a7a769affected · git
    • 0087d9fb3f29f59e8d42c8b058376d80e5adde4c and later · before 61e372122b6d95aec940fdaea0a16f988f359897affected · git
    • 0087d9fb3f29f59e8d42c8b058376d80e5adde4c and later · before 3924aea2c33df3864929c1acd178bfc29d8f005faffected · git
    • 0087d9fb3f29f59e8d42c8b058376d80e5adde4c and later · before 81982a11406c5da6c6e2b188028e7056e16b7128affected · git
    • 0087d9fb3f29f59e8d42c8b058376d80e5adde4c and later · before 94a8cea54cd935c54fa2fba70354757c0fc245e3affected · git
    • before 2.6.29not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.170-16.1.170-1
Debian:13linuxbefore 6.12.85-16.12.85-1
Debian:14linuxbefore 6.18.14-16.18.14-1

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-2026-45918May 27, 2026 · ovpn: tcp - don't deref NULL sk_socket member after tcp_close()
    22Monitor
  • ← EarlierCVE-2026-45919May 27, 2026 · sched/rt: Skip currently executing CPU in rto_next_cpu()
    22Monitor
  • Later →CVE-2026-45921May 27, 2026 · mtd: parsers: Fix memory leak in mtd_parser_tplink_safeloader_parse()
    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 Linux3924aea2c33df3864929c1acd178bfc29d8f005fVendor (CNA)
Linux Linux523d5a4df3c649fa305c89efb552ec62a1ce9d3dVendor (CNA)
Linux Linux55576fa14771d33994c29a9ae960e07bb3f56c20Vendor (CNA)
Linux Linux61e372122b6d95aec940fdaea0a16f988f359897Vendor (CNA)
Linux Linux81982a11406c5da6c6e2b188028e7056e16b7128Vendor (CNA)
Linux Linux94a8cea54cd935c54fa2fba70354757c0fc245e3Vendor (CNA)
Linux Linuxca408af08544d96769c93a3d81a7f63f61129e95Vendor (CNA)
Linux Linuxdbc4e10619ed87a50e637b96f2e574df36a7a769Vendor (CNA)
debian:linux6.1.170-1 · 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-2026-4341419 days apartscsi: qla2xxx: Completely fix fcport double free
    39Monitor
  • CVE-2026-4301126 days apartnet/x25: Fix potential double free of skb
    39Monitor
  • CVE-2026-5299328 days aparttipc: fix double-free in tipc_buf_append()
    39Monitor
  • CVE-2026-3160833 days apartsmb: server: avoid double-free in smb_direct_free_sendmsg after smb_direct_flush_send_list()
    39Monitor
  • CVE-2026-3160933 days apartsmb: client: avoid double-free in smbd_free_send_io() after smbd_send_batch_flush()
    39Monitor
  • CVE-2026-6388853 days apartscsi: target: iscsi: Fix CRC overread and double-free in iscsit_handle_text_cmd()
    39Monitor

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

Weakness class (CWE)

CWE-415 · Double Free

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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 (7 more)

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

All records