NVD / CVE Program· CNA Linux

CVE-2026-31702: f2fs: fix use-after-free of sbi in f2fs_compress_write_end_io()

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: 0.11% (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 2c97dcb6147c8f7f25c629b93be1e69617de5d4a, 39d4ee19c1e7d753dd655aebee632271b171f43a, 57bc678f36ac03281e877c6b84877b43f964143f; azl3 kernel 6.6.134.1-2 on Azure Linux 3.0 6.6.137.1-2.

Low priority for now. Upgrade to Linux Linux 2c97dcb6147c8f7f25c629b93be1e69617de5d4a, 39d4ee19c1e7d753dd655aebee632271b171f43a, 57bc678f36ac03281e877c6b84877b43f964143f; azl3 kernel 6.6.134.1-2 on Azure Linux 3.0 6.6.137.1-2 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: f2fs: fix use-after-free of sbi in f2fs_compress_write_end_io() In f2fs_compress_write_end_io(), dec_page_count(sbi, type) can bring the F2FS_WB_CP_DATA counter to zero, unblocking f2fs_wait_on_all_pages() in f2fs_put_super() on a concurrent unmount CPU. The unmount path then proceeds to call f2fs_destroy_page_array_cache(sbi), which destroys sbi->page_array_slab via kmem_cache_destroy(), and eventually kfree(sbi). Meanwhile, the bio completion callback is still executing: when it reaches page_array_free(sbi, ...), it dereferences sbi->page_array_slab — a destroyed slab cache — to call kmem_cache_free(), causing a use-after-free. This is the same class of bug as CVE-2026-23234 (which fixed the equivalent race in f2fs_write_end_io() in data.c), but in the compressed writeback completion path that was not covered by that fix. Fix this by moving dec_page_count() to after page_array_free(), so that all sbi accesses complete before the counter decrement that can unblock unmount. For non-last folios (where atomic_dec_return on cic->pending_pages is nonzero), dec_page_count is called immediately before returning — page_array_free is not reached on this path, so there is no post-decrement sbi access. For the last folio, page_array_free runs while the F2FS_WB_CP_DATA counter is still nonzero (this folio has not yet decremented it), keeping sbi alive, and dec_page_count runs as the final operation.

HighCVSS 7.8 · v3.1—No exploit Fix available

Memory safety

openSUSE-SU-2026:10793-1

Published: May 1, 2026
Updated: Jun 17, 2026
EPSS: 0.1% · 1th percentile
CWE: CWE-416

Report tools

JSON

Action score

Monitor

Low priority for now.

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

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No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

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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.

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 kernel5.6 and later · before 6.6.136
linux linux kernel6.7 and later · before 6.12.84
linux linux kernel6.13 and later · before 6.18.25
linux linux kernel6.19 and later · before 7.0.2
linux linux kernel7.1

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
- 5.6affected
- 4c8ff7095bef64fc47e996a938f7d57f9e077da3 and later · before 57bc678f36ac03281e877c6b84877b43f964143faffected · git
- 4c8ff7095bef64fc47e996a938f7d57f9e077da3 and later · before ef57cd3329b40c739b9a2e1a8a21ecc4171c6280affected · git
- 4c8ff7095bef64fc47e996a938f7d57f9e077da3 and later · before f5154cf3ce1c8193f0c1891d3769f62740cfe6feaffected · git
- 4c8ff7095bef64fc47e996a938f7d57f9e077da3 and later · before c76cf339b87975ae5b2c06d2d774d5667d25a12aaffected · git
- 4c8ff7095bef64fc47e996a938f7d57f9e077da3 and later · before 2c97dcb6147c8f7f25c629b93be1e69617de5d4aaffected · git
- 4c8ff7095bef64fc47e996a938f7d57f9e077da3 and later · before 39d4ee19c1e7d753dd655aebee632271b171f43aaffected · git
- before 5.6not affected · semver
- 6.1.175 and later · up to and including 6.1.*not affected · semver
- 6.6.136 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.

Ecosystem	Package	Affected range	Fix
Debian:12	linux	before 6.1.176-1	6.1.176-1
Debian:13	linux	before 6.12.85-1	6.12.85-1
Debian:14	linux	before 7.0.3-1	7.0.3-1
openSUSE:Tumbleweed	kernel-source	before 7.0.7-1.1	7.0.7-1.1

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
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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
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-2026-31695May 1, 2026 · wifi: virt_wifi: remove SET_NETDEV_DEV to avoid use-after-free
31Monitor
← EarlierCVE-2026-31701May 1, 2026 · ALSA: caiaq: take a reference on the USB device in create_card()
22Monitor
Later →CVE-2026-31703May 1, 2026 · writeback: Fix use after free in inode_switch_wbs_work_fn()
31Monitor

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	2c97dcb6147c8f7f25c629b93be1e69617de5d4a	Vendor (CNA)
Linux Linux	39d4ee19c1e7d753dd655aebee632271b171f43a	Vendor (CNA)
Linux Linux	57bc678f36ac03281e877c6b84877b43f964143f	Vendor (CNA)
Linux Linux	c76cf339b87975ae5b2c06d2d774d5667d25a12a	Vendor (CNA)
Linux Linux	ef57cd3329b40c739b9a2e1a8a21ecc4171c6280	Vendor (CNA)
Linux Linux	f5154cf3ce1c8193f0c1891d3769f62740cfe6fe	Vendor (CNA)
azl3 kernel 6.6.134.1-2 on Azure Linux 3.0	6.6.137.1-2 · CBL-Mariner Releases	Microsoft (MSRC)
debian:linux	6.1.176-1 · Debian:12	Package registry (OSV)
opensuse:kernel-source	7.0.7-1.1 · openSUSE:Tumbleweed	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, 10:11 PM UTC

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

References

git.kernel.org/stable/c/2c97dcb6147c8f7f25c629b93be1e69617de5d4a

Show all references (5 more)

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

All records