CVE-2026-31448: ext4: avoid infinite loops caused by residual data
Noroxi assessment
Priority: Monitor (action score 37/100)
- 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: 0.49% (FIRST EPSS).
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
- According to CISA the attack is automatable: targets can be found by mass scanning.
- Fixed version: Linux Linux 3a7667595bcad84da53fc156a418e110267c3412, 416c86f30f91b4fb2642ef6b102596ca898f41a5, 5422fe71d26d42af6c454ca9527faaad4e677d6c; azl3 kernel 6.6.130.1-3 on Azure Linux 3.0 6.6.134.1-2.
Low priority for now. Upgrade to Linux Linux 3a7667595bcad84da53fc156a418e110267c3412, 416c86f30f91b4fb2642ef6b102596ca898f41a5, 5422fe71d26d42af6c454ca9527faaad4e677d6c; azl3 kernel 6.6.130.1-3 on Azure Linux 3.0 6.6.134.1-2 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: ext4: avoid infinite loops caused by residual data On the mkdir/mknod path, when mapping logical blocks to physical blocks, if inserting a new extent into the extent tree fails (in this example, because the file system disabled the huge file feature when marking the inode as dirty), ext4_ext_map_blocks() only calls ext4_free_blocks() to reclaim the physical block without deleting the corresponding data in the extent tree. This causes subsequent mkdir operations to reference the previously reclaimed physical block number again, even though this physical block is already being used by the xattr block. Therefore, a situation arises where both the directory and xattr are using the same buffer head block in memory simultaneously. The above causes ext4_xattr_block_set() to enter an infinite loop about "inserted" and cannot release the inode lock, ultimately leading to the 143s blocking problem mentioned in [1]. If the metadata is corrupted, then trying to remove some extent space can do even more harm. Also in case EXT4_GET_BLOCKS_DELALLOC_RESERVE was passed, remove space wrongly update quota information. Jan Kara suggests distinguishing between two cases: 1) The error is ENOSPC or EDQUOT - in this case the filesystem is fully consistent and we must maintain its consistency including all the accounting. However these errors can happen only early before we've inserted the extent into the extent tree. So current code works correctly for this case. 2) Some other error - this means metadata is corrupted. We should strive to do as few modifications as possible to limit damage. So I'd just skip freeing of allocated blocks. [1] INFO: task syz.0.17:5995 blocked for more than 143 seconds. Call Trace: inode_lock_nested include/linux/fs.h:1073 [inline] __start_dirop fs/namei.c:2923 [inline] start_dirop fs/namei.c:2934 [inline]
- Published
- Apr 22, 2026
- Updated
- Oct 19, 2026
- EPSS
- 0.4% · 42th percentile
- CWE
- CWE-835
Report tools
Action score
37
Monitor
Low priority for now.
- CVSS
- 37 / 40 · 9.4 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.4%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · Linux
- 9.4
- NVD has not scored this yet; the score shown is the CNA’s.
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 kernel2.6.22.1 and later · before 6.1.168
- linux linux kernel6.2 and later · before 6.6.131
- linux linux kernel6.7 and later · before 6.12.80
- linux linux kernel6.13 and later · before 6.18.21
- linux linux kernel6.19 and later · before 6.19.11
- linux linux kernel2.6.22
- linux linux kernel7.0
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
- 2.6.22affected
- 315054f023d28ee64f308adf8b5737831541776b and later · before c66545e83a802c3851d9be27a41c0479dd29ff0caffected · git
- 315054f023d28ee64f308adf8b5737831541776b and later · before ecc50bfca9b5c2ee6aeef998181689b80477367baffected · git
- 315054f023d28ee64f308adf8b5737831541776b and later · before 3a7667595bcad84da53fc156a418e110267c3412affected · git
- 315054f023d28ee64f308adf8b5737831541776b and later · before 416c86f30f91b4fb2642ef6b102596ca898f41a5affected · git
- 315054f023d28ee64f308adf8b5737831541776b and later · before 64f425b06b3bea9abc8977fd3982779b3ad070c9affected · git
- 315054f023d28ee64f308adf8b5737831541776b and later · before 5422fe71d26d42af6c454ca9527faaad4e677d6caffected · git
- before 2.6.22not affected · semver
- 6.1.168 and later · up to and including 6.1.*not affected · semver
- 6.6.131 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 6.1.170-1 | 6.1.170-1 |
| Debian:13 | linux | before 6.12.85-1 | 6.12.85-1 |
| Debian:14 | linux | before 6.19.11-1 | 6.19.11-1 |
| openSUSE:Leap 16.0 | dtb-aarch64 | before 6.12.0-160000.35.1 | 6.12.0-160000.35.1 |
| openSUSE:Leap 16.0 | kernel-64kb | before 6.12.0-160000.35.1 | 6.12.0-160000.35.1 |
| openSUSE:Leap 16.0 | kernel-azure | before 6.12.0-160000.35.1 | 6.12.0-160000.35.1 |
| openSUSE:Leap 16.0 | kernel-default | before 6.12.0-160000.35.1 | 6.12.0-160000.35.1 |
| openSUSE:Leap 16.0 | kernel-default-base | before 6.12.0-160000.35.1.160000.2.16 | 6.12.0-160000.35.1.160000.2.16 |
| openSUSE:Leap 16.0 | kernel-docs | before 6.12.0-160000.35.1 | 6.12.0-160000.35.1 |
| openSUSE:Leap 16.0 | kernel-kvmsmall | before 6.12.0-160000.35.1 | 6.12.0-160000.35.1 |
| openSUSE:Leap 16.0 | kernel-obs-build | before 6.12.0-160000.35.1 | 6.12.0-160000.35.1 |
| openSUSE:Leap 16.0 | kernel-obs-qa | before 6.12.0-160000.35.1 | 6.12.0-160000.35.1 |
| openSUSE:Leap 16.0 | kernel-rt | before 6.12.0-160000.35.1 | 6.12.0-160000.35.1 |
| openSUSE:Leap 16.0 | kernel-source | before 6.12.0-160000.35.1 | 6.12.0-160000.35.1 |
| openSUSE:Leap 16.0 | kernel-syms | before 6.12.0-160000.35.1 | 6.12.0-160000.35.1 |
| openSUSE:Leap 16.0 | kernel-zfcpdump | before 6.12.0-160000.35.1 | 6.12.0-160000.35.1 |
| SUSE:Linux Enterprise High Availability Extension 16.0 | kernel-default | before 6.12.0-160000.35.1 | 6.12.0-160000.35.1 |
| SUSE:Linux Enterprise Live Patching 15 SP7 | kernel-livepatch-SLE15-SP7_Update_16 | before 1-150700.15.3.2 | 1-150700.15.3.2 |
| SUSE:Linux Enterprise Live Patching 15 SP7 | kernel-livepatch-SLE15-SP7-RT_Update_16 | before 1-150700.1.5.2 | 1-150700.1.5.2 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP7 | kernel-64kb | before 6.4.0-150700.53.60.1 | 6.4.0-150700.53.60.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP7 | kernel-default | before 6.4.0-150700.53.60.1 | 6.4.0-150700.53.60.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP7 | kernel-default-base | before 6.4.0-150700.53.60.1.150700.17.35.4 | 6.4.0-150700.53.60.1.150700.17.35.4 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP7 | kernel-source | before 6.4.0-150700.53.60.1 | 6.4.0-150700.53.60.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP7 | kernel-zfcpdump | before 6.4.0-150700.53.60.1 | 6.4.0-150700.53.60.1 |
+24
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-2026-31446Apr 22, 2026 · ext4: fix use-after-free in update_super_work when racing with umount31Monitor
- ← EarlierCVE-2026-31447Apr 22, 2026 · ext4: reject mount if bigalloc with s_first_data_block != 031Monitor
- Later →CVE-2026-31449Apr 22, 2026 · ext4: validate p_idx bounds in ext4_ext_correct_indexes31Monitor
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 | 3a7667595bcad84da53fc156a418e110267c3412 | Vendor (CNA) |
| Linux Linux | 416c86f30f91b4fb2642ef6b102596ca898f41a5 | Vendor (CNA) |
| Linux Linux | 5422fe71d26d42af6c454ca9527faaad4e677d6c | Vendor (CNA) |
| Linux Linux | 64f425b06b3bea9abc8977fd3982779b3ad070c9 | Vendor (CNA) |
| Linux Linux | c66545e83a802c3851d9be27a41c0479dd29ff0c | Vendor (CNA) |
| Linux Linux | ecc50bfca9b5c2ee6aeef998181689b80477367b | Vendor (CNA) |
| azl3 kernel 6.6.130.1-3 on Azure Linux 3.0 | 6.6.134.1-2 · CBL-Mariner Releases | Microsoft (MSRC) |
| debian:linux | 6.1.170-1 · Debian:12 | Package registry (OSV) |
| opensuse:dtb-aarch64 | 6.12.0-160000.35.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:kernel-64kb | 6.12.0-160000.35.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:kernel-azure | 6.12.0-160000.35.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:kernel-default | 6.12.0-160000.35.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:kernel-default-base | 6.12.0-160000.35.1.160000.2.16 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:kernel-docs | 6.12.0-160000.35.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:kernel-kvmsmall | 6.12.0-160000.35.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:kernel-obs-build | 6.12.0-160000.35.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:kernel-obs-qa | 6.12.0-160000.35.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:kernel-rt | 6.12.0-160000.35.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:kernel-source | 6.12.0-160000.35.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:kernel-syms | 6.12.0-160000.35.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| suse:kernel-64kb | 6.12.0-160000.35.1 · SUSE:Linux Micro 6.2 | Package registry (OSV) |
| suse:kernel-azure | 6.12.0-160000.35.1 · SUSE:Linux Enterprise Server 16.0 | Package registry (OSV) |
| suse:kernel-default | 6.12.0-160000.35.1 · SUSE:Linux Enterprise High Availability Extension 16.0 | Package registry (OSV) |
| suse:kernel-default-base | 6.4.0-47.1.21.24 · SUSE:Linux Micro 6.0 | Package registry (OSV) |
| suse:kernel-docs | 6.12.0-160000.35.1 · SUSE:Linux Enterprise Server 16.0 | Package registry (OSV) |
| suse:kernel-kvmsmall | 6.4.0-47.1 · SUSE:Linux Micro 6.0 | Package registry (OSV) |
| suse:kernel-obs-build | 6.12.0-160000.35.1 · SUSE:Linux Micro Extras 6.2 | Package registry (OSV) |
| suse:kernel-obs-qa | 6.12.0-160000.35.1 · SUSE:Linux Enterprise Server 16.0 | Package registry (OSV) |
| suse:kernel-rt | 6.12.0-160000.35.1 · SUSE:Linux Micro 6.2 | Package registry (OSV) |
| suse:kernel-source | 6.4.0-47.1 · SUSE:Linux Micro 6.0 | Package registry (OSV) |
+2
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-2026-6388988 days apartscsi: scsi_transport_fc: Widen FPIN pname walker counter to u3232Monitor
- CVE-2026-5293363 days apartio_uring/poll: fix signed comparison in io_poll_get_ownership()31Monitor
- CVE-2026-315522 days apartwifi: wlcore: Return -ENOMEM instead of -EAGAIN if there is not enough headroom30Monitor
- CVE-2026-2345119 days apartbonding: prevent potential infinite loop in bond_header_parse()30Monitor
- CVE-2026-4605235 days apartceph: only d_add() negative dentries when they are unhashed30Monitor
- CVE-2026-6396888 days apartipv6: fix possible infinite loop in fib6_select_path()30Monitor
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
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- low · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- Low
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-835 · Loop with Unreachable Exit Condition ('Infinite Loop')CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H
nvd-secondary
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
- SSVC exploitation— → none
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (8 more)Show less
- git.kernel.org/stable/c/416c86f30f91b4fb2642ef6b102596ca898f41a5
- git.kernel.org/stable/c/5422fe71d26d42af6c454ca9527faaad4e677d6c
- git.kernel.org/stable/c/64f425b06b3bea9abc8977fd3982779b3ad070c9
- git.kernel.org/stable/c/c66545e83a802c3851d9be27a41c0479dd29ff0c
- git.kernel.org/stable/c/ecc50bfca9b5c2ee6aeef998181689b80477367b
- cert-portal.siemens.com/productcert/html/ssa-019113.html
- cert-portal.siemens.com/productcert/html/ssa-082556.html
- cert-portal.siemens.com/productcert/html/ssa-457936.html
Vendor advisories and official records. Exploit/PoC links are deliberately left out.