NVD / CVE Program· CNA Linux

CVE-2021-47254: gfs2: Fix use-after-free in gfs2_glock_shrink_scan

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: 0.24% (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 0364742decb0f02bc183404868b82896f7992595, 094bf5670e762afa243d2c41a5c4ab71c7447bf4, 1ab19c5de4c537ec0d9b21020395a5b5a6c059b2.
Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 0364742decb0f02bc183404868b82896f7992595, 094bf5670e762afa243d2c41a5c4ab71c7447bf4, 1ab19c5de4c537ec0d9b21020395a5b5a6c059b2 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: gfs2: Fix use-after-free in gfs2_glock_shrink_scan The GLF_LRU flag is checked under lru_lock in gfs2_glock_remove_from_lru() to remove the glock from the lru list in __gfs2_glock_put(). On the shrink scan path, the same flag is cleared under lru_lock but because of cond_resched_lock(&lru_lock) in gfs2_dispose_glock_lru(), progress on the put side can be made without deleting the glock from the lru list. Keep GLF_LRU across the race window opened by cond_resched_lock(&lru_lock) to ensure correct behavior on both sides - clear GLF_LRU after list_del under lru_lock.

HighCVSS 7.8 · v3.1—No exploit Fix available

Memory safety

Published: May 21, 2024
Updated: Aug 5, 2026
EPSS: 0.2% · 15th 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: partial

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

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.

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 kernel5.11 and later · before 5.12.12
linux linux kernel4.4.181 and later · before 4.4.274
linux linux kernel4.9.180 and later · before 4.9.274
linux linux kernel4.14.123 and later · before 4.14.238
linux linux kernel4.19.47 and later · before 4.19.196
linux linux kernel5.0.20 and later · before 5.1
linux linux kernel5.1.6 and later · before 5.4.127
linux linux kernel5.5 and later · before 5.10.45
linux linux kernel5.13

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
- 1e7a416fb765c9072479dc424780c0937ba99270, dcbdbe13796ffa561510d2686a6318564e728bbd, 5.2affected
- 6948c6bc17d666663a84c124b3176039e64a58f4 and later · before 38ce329534500bf4ae71f81df6a37a406cf187b4affected · git
- b568ed385a18c0ddbe41862b69088b636550a04f and later · before 92869945cc5b78ee8a1ef90336fe070893e3458aaffected · git
- 762bb3528249604bc680a9df635e8995740176de and later · before 0364742decb0f02bc183404868b82896f7992595affected · git
- bac8520892812dada1ac93f27d96317470d24b1f and later · before 094bf5670e762afa243d2c41a5c4ab71c7447bf4affected · git
- 7881ef3f33bb80f459ea6020d1e021fc524a6348 and later · before 86fd5b27db743a0ce0cc245e3a34813b2aa6ec1daffected · git
- 7881ef3f33bb80f459ea6020d1e021fc524a6348 and later · before a61156314b66456ab6a291ed5deba1ebd002ab3caffected · git
- 7881ef3f33bb80f459ea6020d1e021fc524a6348 and later · before e87ef30fe73e7e10d2c85bdcc778dcec24dca553affected · git
- 7881ef3f33bb80f459ea6020d1e021fc524a6348 and later · before 1ab19c5de4c537ec0d9b21020395a5b5a6c059b2affected · git
- 4.4.181 and later · before 4.4.274affected · 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 5.10.46-1	5.10.46-1
SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS	kernel-default-base	before 5.3.18-150200.24.194.1.150200.9.99.1	5.3.18-150200.24.194.1.150200.9.99.1
SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS	kernel-docs	before 5.3.18-150200.24.194.1	5.3.18-150200.24.194.1
SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS	kernel-obs-build	before 5.3.18-150200.24.194.1	5.3.18-150200.24.194.1
SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS	kernel-preempt	before 5.3.18-150200.24.194.1	5.3.18-150200.24.194.1
SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS	kernel-source	before 5.3.18-150200.24.194.1	5.3.18-150200.24.194.1
SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS	kernel-syms	before 5.3.18-150200.24.194.1	5.3.18-150200.24.194.1
SUSE:Linux Enterprise Live Patching 15 SP2	kernel-default	before 5.3.18-150200.24.194.1	5.3.18-150200.24.194.1
SUSE:Linux Enterprise Live Patching 15 SP2	kernel-livepatch-SLE15-SP2_Update_49	before 1-150200.5.3.1	1-150200.5.3.1

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-2021-47252May 21, 2024 · batman-adv: Avoid WARN_ON timing related checks
22Monitor
← EarlierCVE-2021-47253May 21, 2024 · drm/amd/display: Fix potential memory leak in DMUB hw_init
22Monitor
Later →CVE-2021-47255May 21, 2024 · kvm: LAPIC: Restore guard to prevent illegal APIC register access
28Monitor

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	0364742decb0f02bc183404868b82896f7992595	Vendor (CNA)
Linux Linux	094bf5670e762afa243d2c41a5c4ab71c7447bf4	Vendor (CNA)
Linux Linux	1ab19c5de4c537ec0d9b21020395a5b5a6c059b2	Vendor (CNA)
Linux Linux	38ce329534500bf4ae71f81df6a37a406cf187b4	Vendor (CNA)
Linux Linux	4.14.238	Vendor (CNA)
Linux Linux	4.19.196	Vendor (CNA)
Linux Linux	4.4.274	Vendor (CNA)
Linux Linux	4.9.274	Vendor (CNA)
Linux Linux	5.1	Vendor (CNA)
Linux Linux	5.2	Vendor (CNA)
Linux Linux	86fd5b27db743a0ce0cc245e3a34813b2aa6ec1d	Vendor (CNA)
Linux Linux	92869945cc5b78ee8a1ef90336fe070893e3458a	Vendor (CNA)
Linux Linux	a61156314b66456ab6a291ed5deba1ebd002ab3c	Vendor (CNA)
Linux Linux	e87ef30fe73e7e10d2c85bdcc778dcec24dca553	Vendor (CNA)
debian:linux	5.10.46-1 · Debian:12	Package registry (OSV)
suse:kernel-default	5.3.18-150200.24.194.1 · SUSE:Linux Enterprise Live Patching 15 SP2	Package registry (OSV)
suse:kernel-default-base	5.3.18-150200.24.194.1.150200.9.99.1 · SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS	Package registry (OSV)
suse:kernel-docs	5.3.18-150200.24.194.1 · SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS	Package registry (OSV)
suse:kernel-livepatch-SLE15-SP2_Update_49	1-150200.5.3.1 · SUSE:Linux Enterprise Live Patching 15 SP2	Package registry (OSV)
suse:kernel-obs-build	5.3.18-150200.24.194.1 · SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS	Package registry (OSV)
suse:kernel-preempt	5.3.18-150200.24.194.1 · SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS	Package registry (OSV)
suse:kernel-source	5.3.18-150200.24.194.1 · SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS	Package registry (OSV)
suse:kernel-syms	5.3.18-150200.24.194.1 · SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS	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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

TR-24-0519 · May 22, 2024(Linux Kernel Güncellemesi)

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-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/0364742decb0f02bc183404868b82896f7992595

Show all references (7 more)

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

All records