CVE-2024-40910: ax25: Fix refcount imbalance on inbound connections
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: 0.44% (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 3c34fb0bd4a4237592c5ecb5b2e2531900c55774, 4.15, 4.20.
- Severity is disputed: the assigning authority (CNA) scores it 8.8, NVD 5.5.
- Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).
Low priority for now. Upgrade to Linux Linux 3c34fb0bd4a4237592c5ecb5b2e2531900c55774, 4.15, 4.20 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: ax25: Fix refcount imbalance on inbound connections When releasing a socket in ax25_release(), we call netdev_put() to decrease the refcount on the associated ax.25 device. However, the execution path for accepting an incoming connection never calls netdev_hold(). This imbalance leads to refcount errors, and ultimately to kernel crashes. A typical call trace for the above situation will start with one of the following errors: refcount_t: decrement hit 0; leaking memory. refcount_t: underflow; use-after-free. And will then have a trace like: Call Trace: <TASK> ? show_regs+0x64/0x70 ? __warn+0x83/0x120 ? refcount_warn_saturate+0xb2/0x100 ? report_bug+0x158/0x190 ? prb_read_valid+0x20/0x30 ? handle_bug+0x3e/0x70 ? exc_invalid_op+0x1c/0x70 ? asm_exc_invalid_op+0x1f/0x30 ? refcount_warn_saturate+0xb2/0x100 ? refcount_warn_saturate+0xb2/0x100 ax25_release+0x2ad/0x360 __sock_release+0x35/0xa0 sock_close+0x19/0x20 [...] On reboot (or any attempt to remove the interface), the kernel gets stuck in an infinite loop: unregister_netdevice: waiting for ax0 to become free. Usage count = 0 This patch corrects these issues by ensuring that we call netdev_hold() and ax25_dev_hold() for new connections in ax25_accept(). This makes the logic leading to ax25_accept() match the logic for ax25_bind(): in both cases we increment the refcount, which is ultimately decremented in ax25_release().
- Published
- Jul 12, 2024
- Updated
- Aug 5, 2026
- EPSS
- 0.4% · 38th percentile
- CWE
- —
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 · 0.4%
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
- 8.8
- 3.3 point gap
CVSS:3.1/AV:A/AC:L/PR:N/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 kernel5.18 and later · before 6.1.95
- linux linux kernel6.2 and later · before 6.6.35
- linux linux kernel6.7 and later · before 6.9.6
- linux linux kernel6.10
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
- c44a453ffe16eb08acdc6129ac4fa0192dbc0456, de55a1338e6a48ff1e41ea8db1432496fbe2a62b, 9e1e088a57c23251f1cfe9601bbd90ade2ea73b9, b20a5ab0f5fb175750c6bafd4cf12daccf00c738, 452ae92b99062d2f6a34324eaf705a3b7eac9f8b, 534156dd4ed768e30a43de0036f45dca7c54818f, 5.18affected
- 9fd75b66b8f68498454d685dc4ba13192ae069b0 and later · before f4df9d6c8d4e4c818252b0419c2165d66eabd4ebaffected · git
- 9fd75b66b8f68498454d685dc4ba13192ae069b0 and later · before 52100fd74ad07b53a4666feafff1cd11436362d3affected · git
- 9fd75b66b8f68498454d685dc4ba13192ae069b0 and later · before a723a6c8d4831cc8e2c7b0c9f3f0c010d4671964affected · git
- 9fd75b66b8f68498454d685dc4ba13192ae069b0 and later · before 3c34fb0bd4a4237592c5ecb5b2e2531900c55774affected · git
- 4.14.277 and later · before 4.15affected · semver
- 4.19.240 and later · before 4.20affected · semver
- 5.4.190 and later · before 5.5affected · semver
- 5.10.112 and later · before 5.11affected · semver
- 5.15.35 and later · before 5.16affected · 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 6.1.99-1 | 6.1.99-1 |
| Debian:13 | linux | before 6.9.7-1 | 6.9.7-1 |
| openSUSE:Leap 15.5 | kernel-azure | before 5.14.21-150500.33.69.1 | 5.14.21-150500.33.69.1 |
| openSUSE:Leap 15.5 | kernel-rt_debug | before 5.14.21-150500.13.73.1 | 5.14.21-150500.13.73.1 |
| openSUSE:Leap 15.5 | kernel-source-azure | before 5.14.21-150500.33.69.1 | 5.14.21-150500.33.69.1 |
| openSUSE:Leap 15.5 | kernel-source-rt | before 5.14.21-150500.13.73.1 | 5.14.21-150500.13.73.1 |
| openSUSE:Leap 15.5 | kernel-syms-azure | before 5.14.21-150500.33.69.1 | 5.14.21-150500.33.69.1 |
| openSUSE:Leap 15.5 | kernel-syms-rt | before 5.14.21-150500.13.73.1 | 5.14.21-150500.13.73.1 |
| openSUSE:Leap Micro 5.5 | kernel-default | before 5.14.21-150500.55.83.1 | 5.14.21-150500.55.83.1 |
| openSUSE:Leap Micro 5.5 | kernel-default-base | before 5.14.21-150500.55.83.1.150500.6.37.1 | 5.14.21-150500.55.83.1.150500.6.37.1 |
| openSUSE:Leap Micro 5.5 | kernel-rt | before 5.14.21-150500.13.73.1 | 5.14.21-150500.13.73.1 |
| SUSE:Linux Enterprise Live Patching 15 SP5 | kernel-livepatch-SLE15-SP5_Update_20 | before 1-150500.11.3.1 | 1-150500.11.3.1 |
| SUSE:Linux Enterprise Live Patching 15 SP5 | kernel-livepatch-SLE15-SP5-RT_Update_21 | before 1-150500.11.3.1 | 1-150500.11.3.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-default | before 5.14.21-150500.55.83.1 | 5.14.21-150500.55.83.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-default-base | before 5.14.21-150500.55.83.1.150500.6.37.1 | 5.14.21-150500.55.83.1.150500.6.37.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-rt | before 5.14.21-150500.13.73.1 | 5.14.21-150500.13.73.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-source-rt | before 5.14.21-150500.13.73.1 | 5.14.21-150500.13.73.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP5 | kernel-64kb | before 5.14.21-150500.55.83.1 | 5.14.21-150500.55.83.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP5 | kernel-source | before 5.14.21-150500.55.83.1 | 5.14.21-150500.55.83.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP5 | kernel-zfcpdump | before 5.14.21-150500.55.83.1 | 5.14.21-150500.55.83.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP5 | kernel-docs | before 5.14.21-150500.55.83.1 | 5.14.21-150500.55.83.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP5 | kernel-obs-build | before 5.14.21-150500.55.83.1 | 5.14.21-150500.55.83.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP5 | kernel-syms | before 5.14.21-150500.55.83.1 | 5.14.21-150500.55.83.1 |
| SUSE:Linux Enterprise Module for Public Cloud 15 SP5 | kernel-azure | before 5.14.21-150500.33.69.1 | 5.14.21-150500.33.69.1 |
+4
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-2024-40908Jul 12, 2024 · bpf: Set run context for rawtp test_run callback22Monitor
- ← EarlierCVE-2024-40909Jul 12, 2024 · bpf: Fix a potential use-after-free in bpf_link_free()31Monitor
- Later →CVE-2024-40911Jul 12, 2024 · wifi: cfg80211: Lock wiphy in cfg80211_get_station22Monitor
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 | 3c34fb0bd4a4237592c5ecb5b2e2531900c55774 | Vendor (CNA) |
| Linux Linux | 4.15 | Vendor (CNA) |
| Linux Linux | 4.20 | Vendor (CNA) |
| Linux Linux | 5.11 | Vendor (CNA) |
| Linux Linux | 5.16 | Vendor (CNA) |
| Linux Linux | 5.18 | Vendor (CNA) |
| Linux Linux | 5.5 | Vendor (CNA) |
| Linux Linux | 52100fd74ad07b53a4666feafff1cd11436362d3 | Vendor (CNA) |
| Linux Linux | a723a6c8d4831cc8e2c7b0c9f3f0c010d4671964 | Vendor (CNA) |
| Linux Linux | f4df9d6c8d4e4c818252b0419c2165d66eabd4eb | Vendor (CNA) |
| debian:linux | 6.1.99-1 · Debian:12 | Package registry (OSV) |
| opensuse:kernel-azure | 5.14.21-150500.33.69.1 · openSUSE:Leap 15.5 | Package registry (OSV) |
| opensuse:kernel-default | 5.14.21-150500.55.83.1 · openSUSE:Leap Micro 5.5 | Package registry (OSV) |
| opensuse:kernel-default-base | 5.14.21-150500.55.83.1.150500.6.37.1 · openSUSE:Leap Micro 5.5 | Package registry (OSV) |
| opensuse:kernel-rt | 5.14.21-150500.13.73.1 · openSUSE:Leap Micro 5.5 | Package registry (OSV) |
| opensuse:kernel-rt_debug | 5.14.21-150500.13.73.1 · openSUSE:Leap 15.5 | Package registry (OSV) |
| opensuse:kernel-source-azure | 5.14.21-150500.33.69.1 · openSUSE:Leap 15.5 | Package registry (OSV) |
| opensuse:kernel-source-rt | 5.14.21-150500.13.73.1 · openSUSE:Leap 15.5 | Package registry (OSV) |
| opensuse:kernel-syms-azure | 5.14.21-150500.33.69.1 · openSUSE:Leap 15.5 | Package registry (OSV) |
| opensuse:kernel-syms-rt | 5.14.21-150500.13.73.1 · openSUSE:Leap 15.5 | Package registry (OSV) |
| suse:kernel-64kb | 5.14.21-150500.55.83.1 · SUSE:Linux Enterprise Module for Basesystem 15 SP5 | Package registry (OSV) |
| suse:kernel-azure | 5.14.21-150500.33.69.1 · SUSE:Linux Enterprise Module for Public Cloud 15 SP5 | Package registry (OSV) |
| suse:kernel-default | 5.14.21-150500.55.83.1 · SUSE:Linux Enterprise Micro 5.5 | Package registry (OSV) |
| suse:kernel-default-base | 5.14.21-150500.55.83.1.150500.6.37.1 · SUSE:Linux Enterprise Micro 5.5 | Package registry (OSV) |
| suse:kernel-docs | 5.14.21-150500.55.83.1 · SUSE:Linux Enterprise Module for Development Tools 15 SP5 | Package registry (OSV) |
| suse:kernel-livepatch-SLE15-SP5_Update_20 | 1-150500.11.3.1 · SUSE:Linux Enterprise Live Patching 15 SP5 | Package registry (OSV) |
| suse:kernel-obs-build | 5.14.21-150500.55.83.1 · SUSE:Linux Enterprise Module for Development Tools 15 SP5 | Package registry (OSV) |
| suse:kernel-source | 5.14.21-150500.55.83.1 · SUSE:Linux Enterprise Module for Basesystem 15 SP5 | Package registry (OSV) |
| suse:kernel-source-azure | 5.14.21-150500.33.69.1 · SUSE:Linux Enterprise Module for Public Cloud 15 SP5 | Package registry (OSV) |
| suse:kernel-syms | 5.14.21-150500.55.83.1 · SUSE:Linux Enterprise Module for Development Tools 15 SP5 | 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.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
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.
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-24-0942 · Jul 16, 2024(Linux Kernel Güncellemesi)
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)
—
CVSS 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 (4 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.