CVE-2026-46107: dm-thin: fix metadata refcount underflow
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: 0.10% (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 09a65adc7d8bbfce06392cb6d375468e2728ead5, 12161e03d33afce781f68fa11cc6060538862fad, 323d252a4a378834e4fe68298ca61cfc5dd3a460; azl3 kernel 6.6.139.1-1 on Azure Linux 3.0 6.6.141.1-1.
- Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).
Low priority for now. Upgrade to Linux Linux 09a65adc7d8bbfce06392cb6d375468e2728ead5, 12161e03d33afce781f68fa11cc6060538862fad, 323d252a4a378834e4fe68298ca61cfc5dd3a460; azl3 kernel 6.6.139.1-1 on Azure Linux 3.0 6.6.141.1-1 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: dm-thin: fix metadata refcount underflow There's a bug in dm-thin in the function rebalance_children. If the internal btree node has one entry, the code tries to copy all btree entries from the node's child to the node itself and then decrement the child's reference count. If the child node is shared (it has reference count > 1), we won't free it, so there would be two pointers to each of the grandchildren nodes. But the reference counts of the grandchildren is not increased, thus the reference count doesn't match the number of pointers that point to the grandchildren. This results in "device mapper: space map common: unable to decrement block" errors. Fix this bug by incrementing reference counts on the grandchildren if the btree node is shared.
- Published
- May 28, 2026
- Updated
- Oct 19, 2026
- EPSS
- 0.1% · 0th percentile
- CWE
- CWE-191
Report tools
Action score
31
Monitor
Low priority for now.
- CVSS
- 31 / 40 · 7.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.1%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · Linux
- 7.8
- 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 kernel3.2 and later · before 5.10.259
- linux linux kernel5.11 and later · before 5.15.209
- linux linux kernel5.16 and later · before 6.1.175
- linux linux kernel6.2 and later · before 6.6.140
- linux linux kernel6.7 and later · before 6.12.88
- linux linux kernel6.13 and later · before 6.18.30
- linux linux kernel6.19 and later · before 7.0.7
- 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
- 3.2affected
- 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4 and later · before b719d12cb94df345e9ad2715fd0abe9afcaeb111affected · git
- 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4 and later · before f49b41c9eb7c6ff00df27cd49cea210abbadd8adaffected · git
- 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4 and later · before f06f6aededd792a754cd677c02b3d3016d868c2caffected · git
- 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4 and later · before 12161e03d33afce781f68fa11cc6060538862fadaffected · git
- 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4 and later · before 323d252a4a378834e4fe68298ca61cfc5dd3a460affected · git
- 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4 and later · before 85311a585a26640760cd0f3349ab9f2905691044affected · git
- 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4 and later · before 5ec0debbcfd43596e32c1239e993de06a704e04caffected · git
- 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4 and later · before 09a65adc7d8bbfce06392cb6d375468e2728ead5affected · git
- before 3.2not 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 6.12.88-1 | 6.12.88-1 |
| Debian:14 | linux | before 7.0.7-1 | 7.0.7-1 |
| SUSE:Linux Enterprise Live Patching 12 SP5 | kernel-default | before 4.12.14-122.328.1 | 4.12.14-122.328.1 |
| SUSE:Linux Enterprise Live Patching 12 SP5 | kgraft-patch-SLE12-SP5_Update_87 | before 1-8.5.1 | 1-8.5.1 |
| SUSE:Linux Enterprise Server 12 SP5-LTSS | kernel-source | before 4.12.14-122.328.1 | 4.12.14-122.328.1 |
| SUSE:Linux Enterprise Server 12 SP5-LTSS | kernel-syms | before 4.12.14-122.328.1 | 4.12.14-122.328.1 |
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-2026-46239May 28, 2026 · media: i2c: ov5647: Fix runtime PM refcount leak in s_ctrl22Monitor
- ← EarlierCVE-2026-46240May 28, 2026 · media: iris: Fix use-after-free in iris_release_internal_buffers()31Monitor
- Later →CVE-2026-46110May 28, 2026 · net: stmmac: Prevent NULL deref when RX memory exhausted30Monitor
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 | 09a65adc7d8bbfce06392cb6d375468e2728ead5 | Vendor (CNA) |
| Linux Linux | 12161e03d33afce781f68fa11cc6060538862fad | Vendor (CNA) |
| Linux Linux | 323d252a4a378834e4fe68298ca61cfc5dd3a460 | Vendor (CNA) |
| Linux Linux | 5ec0debbcfd43596e32c1239e993de06a704e04c | Vendor (CNA) |
| Linux Linux | 85311a585a26640760cd0f3349ab9f2905691044 | Vendor (CNA) |
| Linux Linux | b719d12cb94df345e9ad2715fd0abe9afcaeb111 | Vendor (CNA) |
| Linux Linux | f06f6aededd792a754cd677c02b3d3016d868c2c | Vendor (CNA) |
| Linux Linux | f49b41c9eb7c6ff00df27cd49cea210abbadd8ad | Vendor (CNA) |
| azl3 kernel 6.6.139.1-1 on Azure Linux 3.0 | 6.6.141.1-1 · CBL-Mariner Releases | Microsoft (MSRC) |
| debian:linux | 6.1.176-1 · Debian:12 | Package registry (OSV) |
| suse:kernel-default | 4.12.14-122.328.1 · SUSE:Linux Enterprise Live Patching 12 SP5 | Package registry (OSV) |
| suse:kernel-source | 4.12.14-122.328.1 · SUSE:Linux Enterprise Server 12 SP5-LTSS | Package registry (OSV) |
| suse:kernel-syms | 4.12.14-122.328.1 · SUSE:Linux Enterprise Server 12 SP5-LTSS | Package registry (OSV) |
| suse:kgraft-patch-SLE12-SP5_Update_87 | 1-8.5.1 · SUSE:Linux Enterprise Live Patching 12 SP5 | 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-2026-5317628 days apartIB/isert: Reject login PDUs shorter than ISER_HEADERS_LEN39Monitor
- CVE-2026-6394052 days apartKVM: SEV: Ignore Port I/O requests of length '0'37Monitor
- CVE-2026-4318722 days apartxfs: delete attr leaf freemap entries when empty35Monitor
- CVE-2026-5317828 days apartstaging: rtl8723bs: rtw_mlme: add bounds checks before ie_length subtraction32Monitor
- CVE-2026-5291927 days apartbatman-adv: fix tp_meter counter underflow during shutdown31Monitor
- CVE-2026-5313027 days apartfs/omfs: reject s_sys_blocksize smaller than OMFS_DIR_START31Monitor
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-26-0290 · Jun 2, 2026(Linux Kernel Güvenlik Bildirimi)
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-191 · Integer Underflow (Wrap or Wraparound)CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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/12161e03d33afce781f68fa11cc6060538862fad
- git.kernel.org/stable/c/323d252a4a378834e4fe68298ca61cfc5dd3a460
- git.kernel.org/stable/c/5ec0debbcfd43596e32c1239e993de06a704e04c
- git.kernel.org/stable/c/85311a585a26640760cd0f3349ab9f2905691044
- git.kernel.org/stable/c/b719d12cb94df345e9ad2715fd0abe9afcaeb111
- git.kernel.org/stable/c/f06f6aededd792a754cd677c02b3d3016d868c2c
- git.kernel.org/stable/c/f49b41c9eb7c6ff00df27cd49cea210abbadd8ad
- cert-portal.siemens.com/productcert/html/ssa-784472.html
Vendor advisories and official records. Exploit/PoC links are deliberately left out.