CVE-2021-47638: ubifs: rename_whiteout: Fix double free for whiteout_ui->data
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: 0.26% (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 14276d38c89a170363e90b6ac0a53c3cf61b87fc, 2ad07009c459e56ebdcc089d850d664660fdb742, 2b3236ecf96db7af5836e1366ce39ace8ce832fa.
- Severity is disputed: the assigning authority (CNA) scores it 7.8, NVD 5.5.
Low priority for now. Upgrade to Linux Linux 14276d38c89a170363e90b6ac0a53c3cf61b87fc, 2ad07009c459e56ebdcc089d850d664660fdb742, 2b3236ecf96db7af5836e1366ce39ace8ce832fa 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: ubifs: rename_whiteout: Fix double free for whiteout_ui->data 'whiteout_ui->data' will be freed twice if space budget fail for rename whiteout operation as following process: rename_whiteout dev = kmalloc whiteout_ui->data = dev kfree(whiteout_ui->data) // Free first time iput(whiteout) ubifs_free_inode kfree(ui->data) // Double free! KASAN reports: ================================================================== BUG: KASAN: double-free or invalid-free in ubifs_free_inode+0x4f/0x70 Call Trace: kfree+0x117/0x490 ubifs_free_inode+0x4f/0x70 [ubifs] i_callback+0x30/0x60 rcu_do_batch+0x366/0xac0 __do_softirq+0x133/0x57f Allocated by task 1506: kmem_cache_alloc_trace+0x3c2/0x7a0 do_rename+0x9b7/0x1150 [ubifs] ubifs_rename+0x106/0x1f0 [ubifs] do_syscall_64+0x35/0x80 Freed by task 1506: kfree+0x117/0x490 do_rename.cold+0x53/0x8a [ubifs] ubifs_rename+0x106/0x1f0 [ubifs] do_syscall_64+0x35/0x80 The buggy address belongs to the object at ffff88810238bed8 which belongs to the cache kmalloc-8 of size 8 ================================================================== Let ubifs_free_inode() free 'whiteout_ui->data'. BTW, delete unused assignment 'whiteout_ui->data_len = 0', process 'ubifs_evict_inode() -> ubifs_jnl_delete_inode() -> ubifs_jnl_write_inode()' doesn't need it (because 'inc_nlink(whiteout)' won't be excuted by 'goto out_release', and the nlink of whiteout inode is 0).
- Published
- Feb 26, 2025
- Updated
- Aug 5, 2026
- EPSS
- 0.2% · 17th percentile
- CWE
- CWE-415
Report tools
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.
CNA vs NVD score
- NVD
- 5.5
- CNA · Linux
- 7.8
- 2.3 point gap
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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.
We use this product, ask for helpAffected 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 kernel4.9 and later · before 4.14.276
- linux linux kernel4.15 and later · before 4.19.238
- linux linux kernel4.20 and later · before 5.4.189
- linux linux kernel5.5 and later · before 5.10.110
- linux linux kernel5.11 and later · before 5.15.33
- linux linux kernel5.16 and later · before 5.16.19
- linux linux kernel5.17 and later · before 5.17.2
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
- 4.9affected
- 9e0a1fff8db56eaaebb74b4a3ef65f86811c4798 and later · before 8b3c7be16f3f4dfd6e15ac651484e59d3fa36274affected · git
- 9e0a1fff8db56eaaebb74b4a3ef65f86811c4798 and later · before 2b3236ecf96db7af5836e1366ce39ace8ce832faaffected · git
- 9e0a1fff8db56eaaebb74b4a3ef65f86811c4798 and later · before 14276d38c89a170363e90b6ac0a53c3cf61b87fcaffected · git
- 9e0a1fff8db56eaaebb74b4a3ef65f86811c4798 and later · before a90e2dbe66d2647ff95a0442ad2e86482d977fd8affected · git
- 9e0a1fff8db56eaaebb74b4a3ef65f86811c4798 and later · before 2ad07009c459e56ebdcc089d850d664660fdb742affected · git
- 9e0a1fff8db56eaaebb74b4a3ef65f86811c4798 and later · before b9a937f096e608b3368c1abc920d4d640ba2c94faffected · git
- 9e0a1fff8db56eaaebb74b4a3ef65f86811c4798 and later · before 6d7a158a7363c1f6604aa47ae1a280a5c65123ddaffected · git
- 9e0a1fff8db56eaaebb74b4a3ef65f86811c4798 and later · before 40a8f0d5e7b3999f096570edab71c345da812e3eaffected · git
- before 4.9not 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 5.17.3-1 | 5.17.3-1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-64kb | before 5.14.21-150400.24.158.1 | 5.14.21-150400.24.158.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-docs | before 5.14.21-150400.24.158.1 | 5.14.21-150400.24.158.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-obs-build | before 5.14.21-150400.24.158.1 | 5.14.21-150400.24.158.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-source | before 5.14.21-150400.24.158.1 | 5.14.21-150400.24.158.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-syms | before 5.14.21-150400.24.158.1 | 5.14.21-150400.24.158.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | kernel-64kb | before 5.14.21-150500.55.100.1 | 5.14.21-150500.55.100.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | kernel-docs | before 5.14.21-150500.55.100.1 | 5.14.21-150500.55.100.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | kernel-obs-build | before 5.14.21-150500.55.100.1 | 5.14.21-150500.55.100.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | kernel-syms | before 5.14.21-150500.55.100.1 | 5.14.21-150500.55.100.1 |
| SUSE:Linux Enterprise Live Patching 15 SP4 | kernel-livepatch-SLE15-SP4_Update_38 | before 1-150400.9.3.1 | 1-150400.9.3.1 |
| SUSE:Linux Enterprise Live Patching 15 SP5 | kernel-livepatch-SLE15-SP5_Update_25 | before 1-150500.11.3.1 | 1-150500.11.3.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-default | before 5.14.21-150400.24.158.1 | 5.14.21-150400.24.158.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-default-base | before 5.14.21-150400.24.158.1.150400.24.78.1 | 5.14.21-150400.24.158.1.150400.24.78.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-rt | before 5.14.21-150400.15.115.1 | 5.14.21-150400.15.115.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-source-rt | before 5.14.21-150400.15.115.1 | 5.14.21-150400.15.115.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-default | before 5.14.21-150500.55.100.1 | 5.14.21-150500.55.100.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-default-base | before 5.14.21-150500.55.100.1.150500.6.47.1 | 5.14.21-150500.55.100.1.150500.6.47.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-rt | before 5.14.21-150500.13.91.1 | 5.14.21-150500.13.91.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-source | before 5.14.21-150500.55.100.1 | 5.14.21-150500.55.100.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-source-rt | before 5.14.21-150500.13.91.1 | 5.14.21-150500.13.91.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-zfcpdump | before 5.14.21-150400.24.158.1 | 5.14.21-150400.24.158.1 |
| SUSE:Linux Enterprise Server 15 SP5-LTSS | kernel-zfcpdump | before 5.14.21-150500.55.100.1 | 5.14.21-150500.55.100.1 |
Same product
linux: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV90Now
- 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 KEV89Now
- CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV85Now
Published before and after this one in the same product
- ← EarlierCVE-2021-47636Feb 26, 2025 · ubifs: Fix read out-of-bounds in ubifs_wbuf_write_nolock()28Monitor
- ← EarlierCVE-2021-47637Feb 26, 2025 · ubifs: Fix deadlock in concurrent rename whiteout and inode writeback22Monitor
- Later →CVE-2021-47639Feb 26, 2025 · KVM: x86/mmu: Zap _all_ roots when unmapping gfn range in TDP MMU31Monitor
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 | 14276d38c89a170363e90b6ac0a53c3cf61b87fc | Vendor (CNA) |
| Linux Linux | 2ad07009c459e56ebdcc089d850d664660fdb742 | Vendor (CNA) |
| Linux Linux | 2b3236ecf96db7af5836e1366ce39ace8ce832fa | Vendor (CNA) |
| Linux Linux | 40a8f0d5e7b3999f096570edab71c345da812e3e | Vendor (CNA) |
| Linux Linux | 6d7a158a7363c1f6604aa47ae1a280a5c65123dd | Vendor (CNA) |
| Linux Linux | 8b3c7be16f3f4dfd6e15ac651484e59d3fa36274 | Vendor (CNA) |
| Linux Linux | a90e2dbe66d2647ff95a0442ad2e86482d977fd8 | Vendor (CNA) |
| Linux Linux | b9a937f096e608b3368c1abc920d4d640ba2c94f | Vendor (CNA) |
| debian:linux | 5.17.3-1 · Debian:12 | Package registry (OSV) |
| suse:kernel-64kb | 5.14.21-150400.24.158.1 · SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | Package registry (OSV) |
| suse:kernel-default | 5.14.21-150400.24.158.1 · SUSE:Linux Enterprise Micro 5.3 | Package registry (OSV) |
| suse:kernel-default-base | 5.14.21-150400.24.158.1.150400.24.78.1 · SUSE:Linux Enterprise Micro 5.3 | Package registry (OSV) |
| suse:kernel-docs | 5.14.21-150400.24.158.1 · SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | Package registry (OSV) |
| suse:kernel-livepatch-SLE15-SP4_Update_38 | 1-150400.9.3.1 · SUSE:Linux Enterprise Live Patching 15 SP4 | Package registry (OSV) |
| suse:kernel-livepatch-SLE15-SP5_Update_25 | 1-150500.11.3.1 · SUSE:Linux Enterprise Live Patching 15 SP5 | Package registry (OSV) |
| suse:kernel-obs-build | 5.14.21-150400.24.158.1 · SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | Package registry (OSV) |
| suse:kernel-rt | 5.14.21-150500.13.91.1 · SUSE:Linux Enterprise Micro 5.5 | Package registry (OSV) |
| suse:kernel-source | 5.14.21-150400.24.158.1 · SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | Package registry (OSV) |
| suse:kernel-source-rt | 5.14.21-150500.13.91.1 · SUSE:Linux Enterprise Micro 5.5 | Package registry (OSV) |
| suse:kernel-syms | 5.14.21-150400.24.158.1 · SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | Package registry (OSV) |
| suse:kernel-zfcpdump | 5.14.21-150400.24.158.1 · SUSE:Linux Enterprise Server 15 SP4-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 researchersFinders, 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-2026-31608422 days apartsmb: server: avoid double-free in smb_direct_free_sendmsg after smb_direct_flush_send_list()39Monitor
- CVE-2026-31609422 days apartsmb: client: avoid double-free in smbd_free_send_io() after smbd_send_batch_flush()39Monitor
- CVE-2026-43011429 days apartnet/x25: Fix potential double free of skb39Monitor
- CVE-2026-43414436 days apartscsi: qla2xxx: Completely fix fcport double free39Monitor
- CVE-2026-52993483 days aparttipc: fix double-free in tipc_buf_append()39Monitor
- CVE-2026-63888508 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).
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-415 · Double FreeCVSS 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
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (7 more)Show less
- git.kernel.org/stable/c/2ad07009c459e56ebdcc089d850d664660fdb742
- git.kernel.org/stable/c/2b3236ecf96db7af5836e1366ce39ace8ce832fa
- git.kernel.org/stable/c/40a8f0d5e7b3999f096570edab71c345da812e3e
- git.kernel.org/stable/c/6d7a158a7363c1f6604aa47ae1a280a5c65123dd
- git.kernel.org/stable/c/8b3c7be16f3f4dfd6e15ac651484e59d3fa36274
- git.kernel.org/stable/c/a90e2dbe66d2647ff95a0442ad2e86482d977fd8
- git.kernel.org/stable/c/b9a937f096e608b3368c1abc920d4d640ba2c94f
Vendor advisories and official records. Exploit/PoC links are deliberately left out.