NVD / CVE Program· CNA Linux

CVE-2024-56759: btrfs: fix use-after-free when COWing tree bock and tracing is enabled

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: 0.22% (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 44f52bbe96dfdbe4aca3818a2534520082a07040, 526ff5b27f090fb15040471f892cd2c9899ce314, 66376f1a73cba57fd0af2631d7888605b738e499.

Low priority for now. Upgrade to Linux Linux 44f52bbe96dfdbe4aca3818a2534520082a07040, 526ff5b27f090fb15040471f892cd2c9899ce314, 66376f1a73cba57fd0af2631d7888605b738e499 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: fix use-after-free when COWing tree bock and tracing is enabled When a COWing a tree block, at btrfs_cow_block(), and we have the tracepoint trace_btrfs_cow_block() enabled and preemption is also enabled (CONFIG_PREEMPT=y), we can trigger a use-after-free in the COWed extent buffer while inside the tracepoint code. This is because in some paths that call btrfs_cow_block(), such as btrfs_search_slot(), we are holding the last reference on the extent buffer @buf so btrfs_force_cow_block() drops the last reference on the @buf extent buffer when it calls free_extent_buffer_stale(buf), which schedules the release of the extent buffer with RCU. This means that if we are on a kernel with preemption, the current task may be preempted before calling trace_btrfs_cow_block() and the extent buffer already released by the time trace_btrfs_cow_block() is called, resulting in a use-after-free. Fix this by moving the trace_btrfs_cow_block() from btrfs_cow_block() to btrfs_force_cow_block() before the COWed extent buffer is freed. This also has a side effect of invoking the tracepoint in the tree defrag code, at defrag.c:btrfs_realloc_node(), since btrfs_force_cow_block() is called there, but this is fine and it was actually missing there.

HighCVSS 7.8 · v3.1—No exploit Fix available

Memory safety

Published: Jan 6, 2025
Updated: Aug 5, 2026
EPSS: 0.2% · 12th percentile
CWE: CWE-416

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 31 / 40 · 7.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.2%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: 7.8
CNA · Linux: 7.8; 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.

ProductVersion

Vendor	Product	CPE
linux	linux kernel	cpe:2.3:o:linux:linux_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 6.12.8
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
- 3.4affected
- 3083ee2e18b701122a3b841db83448543a87a583 and later · before ba5120a2fb5f23b4d39d302e181aa5d4e28a90d1affected · git
- 3083ee2e18b701122a3b841db83448543a87a583 and later · before 526ff5b27f090fb15040471f892cd2c9899ce314affected · git
- 3083ee2e18b701122a3b841db83448543a87a583 and later · before 66376f1a73cba57fd0af2631d7888605b738e499affected · git
- 3083ee2e18b701122a3b841db83448543a87a583 and later · before 9a466b8693b9add05de99af00c7bdff8259ecf19affected · git
- 3083ee2e18b701122a3b841db83448543a87a583 and later · before c3a403d8ce36f5a809a492581de5ad17843e4701affected · git
- 3083ee2e18b701122a3b841db83448543a87a583 and later · before 44f52bbe96dfdbe4aca3818a2534520082a07040affected · git
- before 3.4not affected · semver
- 5.10.233 and later · up to and including 5.10.*not affected · semver
- 5.15.176 and later · up to and including 5.15.*not affected · semver

Package-level exposure

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

Ecosystem	Package	Affected range	Fix
Debian:12	linux	before 6.1.124-1	6.1.124-1
Debian:13	linux	before 6.12.8-1	6.12.8-1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS	kernel-64kb	before 5.3.18-150300.59.195.1	5.3.18-150300.59.195.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS	kernel-default-base	before 5.3.18-150300.59.195.1.150300.18.116.1	5.3.18-150300.59.195.1.150300.18.116.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS	kernel-docs	before 5.3.18-150300.59.195.1	5.3.18-150300.59.195.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS	kernel-obs-build	before 5.3.18-150300.59.195.1	5.3.18-150300.59.195.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS	kernel-preempt	before 5.3.18-150300.59.195.1	5.3.18-150300.59.195.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS	kernel-source	before 5.3.18-150300.59.195.1	5.3.18-150300.59.195.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS	kernel-syms	before 5.3.18-150300.59.195.1	5.3.18-150300.59.195.1
SUSE:Linux Enterprise Live Patching 15 SP3	kernel-default	before 5.3.18-150300.59.195.1	5.3.18-150300.59.195.1
SUSE:Linux Enterprise Live Patching 15 SP3	kernel-livepatch-SLE15-SP3_Update_54	before 1-150300.7.3.1	1-150300.7.3.1
SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME CORE	kernel-default	before 3.0.101-108.177.1	3.0.101-108.177.1
SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME CORE	kernel-ec2	before 3.0.101-108.177.1	3.0.101-108.177.1
SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME CORE	kernel-source	before 3.0.101-108.177.1	3.0.101-108.177.1
SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME CORE	kernel-syms	before 3.0.101-108.177.1	3.0.101-108.177.1
SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME CORE	kernel-trace	before 3.0.101-108.177.1	3.0.101-108.177.1
SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME CORE	kernel-xen	before 3.0.101-108.177.1	3.0.101-108.177.1
SUSE:Linux Enterprise Server 15 SP3-LTSS	kernel-zfcpdump	before 5.3.18-150300.59.195.1	5.3.18-150300.59.195.1

Same product

linux: all records

Other highest-scoring records for the same primary product.

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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
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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-2024-56757Jan 6, 2025 · Bluetooth: btusb: mediatek: add intf release flow when usb disconnect
22Monitor
← EarlierCVE-2024-56758Jan 6, 2025 · btrfs: check folio mapping after unlock in relocate_one_folio()
22Monitor
Later →CVE-2024-56760Jan 6, 2025 · PCI/MSI: Handle lack of irqdomain gracefully
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 / package	Fixed version	Source
Linux Linux	44f52bbe96dfdbe4aca3818a2534520082a07040	Vendor (CNA)
Linux Linux	526ff5b27f090fb15040471f892cd2c9899ce314	Vendor (CNA)
Linux Linux	66376f1a73cba57fd0af2631d7888605b738e499	Vendor (CNA)
Linux Linux	9a466b8693b9add05de99af00c7bdff8259ecf19	Vendor (CNA)
Linux Linux	ba5120a2fb5f23b4d39d302e181aa5d4e28a90d1	Vendor (CNA)
Linux Linux	c3a403d8ce36f5a809a492581de5ad17843e4701	Vendor (CNA)
debian:linux	6.1.124-1 · Debian:12	Package registry (OSV)
suse:kernel-64kb	5.3.18-150300.59.195.1 · SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS	Package registry (OSV)
suse:kernel-default	3.0.101-108.177.1 · SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME CORE	Package registry (OSV)
suse:kernel-default-base	5.3.18-150300.59.195.1.150300.18.116.1 · SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS	Package registry (OSV)
suse:kernel-docs	5.3.18-150300.59.195.1 · SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS	Package registry (OSV)
suse:kernel-ec2	3.0.101-108.177.1 · SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME CORE	Package registry (OSV)
suse:kernel-livepatch-SLE15-SP3_Update_54	1-150300.7.3.1 · SUSE:Linux Enterprise Live Patching 15 SP3	Package registry (OSV)
suse:kernel-obs-build	5.3.18-150300.59.195.1 · SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS	Package registry (OSV)
suse:kernel-preempt	5.3.18-150300.59.195.1 · SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS	Package registry (OSV)
suse:kernel-source	3.0.101-108.177.1 · SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME CORE	Package registry (OSV)
suse:kernel-syms	3.0.101-108.177.1 · SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME CORE	Package registry (OSV)
suse:kernel-trace	3.0.101-108.177.1 · SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME CORE	Package registry (OSV)
suse:kernel-xen	3.0.101-108.177.1 · SUSE:Linux Enterprise Server 11 SP4 LTSS EXTREME CORE	Package 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.

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: 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-416 · Use After Free

CVSS vector

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

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1free(dev->buf);
2/* ... another thread is still running ... */
3process(dev->buf);

Fixed

1lock(&dev->lock);
2free(dev->buf);
3dev->buf = NULL;
4unlock(&dev->lock);

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

Fix✗ → ✓Sep 28, 2026, 10:09 PM UTC

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

References

git.kernel.org/stable/c/44f52bbe96dfdbe4aca3818a2534520082a07040

Show all references (7 more)

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

All records