CVE-2021-46904: net: hso: fix null-ptr-deref during tty device unregistration
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: 0.25% (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 145c89c441d27696961752bf51b323f347601bee, 388d05f70f1ee0cac4a2068fd295072f1a44152a, 4a2933c88399c0ebc738db39bbce3ae89786d723.
- Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).
Low priority for now. Upgrade to Linux Linux 145c89c441d27696961752bf51b323f347601bee, 388d05f70f1ee0cac4a2068fd295072f1a44152a, 4a2933c88399c0ebc738db39bbce3ae89786d723 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: net: hso: fix null-ptr-deref during tty device unregistration Multiple ttys try to claim the same the minor number causing a double unregistration of the same device. The first unregistration succeeds but the next one results in a null-ptr-deref. The get_free_serial_index() function returns an available minor number but doesn't assign it immediately. The assignment is done by the caller later. But before this assignment, calls to get_free_serial_index() would return the same minor number. Fix this by modifying get_free_serial_index to assign the minor number immediately after one is found to be and rename it to obtain_minor() to better reflect what it does. Similary, rename set_serial_by_index() to release_minor() and modify it to free up the minor number of the given hso_serial. Every obtain_minor() should have corresponding release_minor() call.
- Published
- Feb 26, 2024
- Updated
- Jun 17, 2026
- EPSS
- 0.2% · 17th percentile
- CWE
- CWE-476
Report tools
Action score
22
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.
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.
Is your version affected? Check itNoroxi 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 |
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
- 2.6.27affected
- 72dc1c096c7051a48ab1dbb12f71976656b55eb5 and later · before a462067d7c8e6953a733bf5ade8db947b1bb5449affected · git
- 72dc1c096c7051a48ab1dbb12f71976656b55eb5 and later · before 145c89c441d27696961752bf51b323f347601beeaffected · git
- 72dc1c096c7051a48ab1dbb12f71976656b55eb5 and later · before caf5ac93b3b5d5fac032fc11fbea680e115421b4affected · git
- 72dc1c096c7051a48ab1dbb12f71976656b55eb5 and later · before 92028d7a31e55d53e41cff679156b9432cffcb36affected · git
- 72dc1c096c7051a48ab1dbb12f71976656b55eb5 and later · before 4a2933c88399c0ebc738db39bbce3ae89786d723affected · git
- 72dc1c096c7051a48ab1dbb12f71976656b55eb5 and later · before dc195928d7e4ec7b5cfc6cd10dc4c8d87a7c72acaffected · git
- 72dc1c096c7051a48ab1dbb12f71976656b55eb5 and later · before 388d05f70f1ee0cac4a2068fd295072f1a44152aaffected · git
- 72dc1c096c7051a48ab1dbb12f71976656b55eb5 and later · before 8a12f8836145ffe37e9c8733dce18c22fb668b66affected · git
- before 2.6.27not affected · semver
Affected versions · NVD (7)
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- linux linux kernel2.6.27 and later · before 4.4.268
- linux linux kernel4.5.0 and later · before 4.9.268
- linux linux kernel4.10.0 and later · before 4.14.232
- linux linux kernel4.15.0 and later · before 4.19.187
- linux linux kernel4.20.0 and later · before 5.4.112
- linux linux kernel5.5.0 and later · before 5.10.30
- linux linux kernel5.11.0 and later · before 5.11.14
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 5.10.38-1 | 5.10.38-1 |
| SUSE:Linux Enterprise High Availability Extension 12 SP5 | kernel-default | before 4.12.14-122.216.1 | 4.12.14-122.216.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS | kernel-default-base | before 5.3.18-150200.24.183.1.150200.9.93.2 | 5.3.18-150200.24.183.1.150200.9.93.2 |
| SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS | kernel-docs | before 5.3.18-150200.24.183.1 | 5.3.18-150200.24.183.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS | kernel-obs-build | before 5.3.18-150200.24.183.1 | 5.3.18-150200.24.183.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS | kernel-preempt | before 5.3.18-150200.24.183.1 | 5.3.18-150200.24.183.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS | kernel-source | before 5.3.18-150200.24.183.1 | 5.3.18-150200.24.183.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP2-LTSS | kernel-syms | before 5.3.18-150200.24.183.1 | 5.3.18-150200.24.183.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS | kernel-64kb | before 5.3.18-150300.59.153.2 | 5.3.18-150300.59.153.2 |
| SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS | kernel-default-base | before 5.3.18-150300.59.153.2.150300.18.90.2 | 5.3.18-150300.59.153.2.150300.18.90.2 |
| SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS | kernel-docs | before 5.3.18-150300.59.153.2 | 5.3.18-150300.59.153.2 |
| SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS | kernel-obs-build | before 5.3.18-150300.59.153.2 | 5.3.18-150300.59.153.2 |
| SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS | kernel-preempt | before 5.3.18-150300.59.153.2 | 5.3.18-150300.59.153.2 |
| SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS | kernel-source | before 5.3.18-150300.59.153.2 | 5.3.18-150300.59.153.2 |
| SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS | kernel-syms | before 5.3.18-150300.59.153.1 | 5.3.18-150300.59.153.1 |
| SUSE:Linux Enterprise Live Patching 12 SP5 | kgraft-patch-SLE12-SP5_Update_56 | before 1-8.3.1 | 1-8.3.1 |
| SUSE:Linux Enterprise Live Patching 15 SP2 | kernel-default | before 5.3.18-150200.24.183.1 | 5.3.18-150200.24.183.1 |
| SUSE:Linux Enterprise Live Patching 15 SP2 | kernel-livepatch-SLE15-SP2_Update_46 | before 1-150200.5.3.2 | 1-150200.5.3.2 |
| SUSE:Linux Enterprise Live Patching 15 SP3 | kernel-default | before 5.3.18-150300.59.153.2 | 5.3.18-150300.59.153.2 |
| SUSE:Linux Enterprise Live Patching 15 SP3 | kernel-livepatch-SLE15-SP3_Update_42 | before 1-150300.7.3.2 | 1-150300.7.3.2 |
| SUSE:Linux Enterprise Micro 5.1 | kernel-rt | before 5.3.18-150300.161.1 | 5.3.18-150300.161.1 |
| SUSE:Linux Enterprise Micro 5.1 | kernel-source-rt | before 5.3.18-150300.161.1 | 5.3.18-150300.161.1 |
| SUSE:Linux Enterprise Real Time 12 SP5 | kernel-rt | before 4.12.14-10.182.1 | 4.12.14-10.182.1 |
| SUSE:Linux Enterprise Real Time 12 SP5 | kernel-rt_debug | before 4.12.14-10.182.1 | 4.12.14-10.182.1 |
+16
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-2023-52458Feb 23, 2024 · block: add check that partition length needs to be aligned with block size22Monitor
- ← EarlierCVE-2023-52464Feb 23, 2024 · EDAC/thunderx: Fix possible out-of-bounds string access31Monitor
- Later →CVE-2021-46905Feb 26, 2024 · net: hso: fix NULL-deref on disconnect regression22Monitor
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 | 145c89c441d27696961752bf51b323f347601bee | Vendor (CNA) |
| Linux Linux | 388d05f70f1ee0cac4a2068fd295072f1a44152a | Vendor (CNA) |
| Linux Linux | 4a2933c88399c0ebc738db39bbce3ae89786d723 | Vendor (CNA) |
| Linux Linux | 8a12f8836145ffe37e9c8733dce18c22fb668b66 | Vendor (CNA) |
| Linux Linux | 92028d7a31e55d53e41cff679156b9432cffcb36 | Vendor (CNA) |
| Linux Linux | a462067d7c8e6953a733bf5ade8db947b1bb5449 | Vendor (CNA) |
| Linux Linux | caf5ac93b3b5d5fac032fc11fbea680e115421b4 | Vendor (CNA) |
| Linux Linux | dc195928d7e4ec7b5cfc6cd10dc4c8d87a7c72ac | Vendor (CNA) |
| debian:linux | 5.10.38-1 · Debian:12 | Package registry (OSV) |
| suse:kernel-64kb | 5.3.18-150300.59.153.2 · SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS | Package registry (OSV) |
| suse:kernel-default | 5.3.18-150300.59.153.2 · SUSE:Linux Enterprise Live Patching 15 SP3 | Package registry (OSV) |
| suse:kernel-default-base | 5.3.18-150300.59.153.2.150300.18.90.2 · SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS | Package registry (OSV) |
| suse:kernel-docs | 5.3.18-150300.59.153.2 · SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS | Package registry (OSV) |
| suse:kernel-livepatch-SLE15-SP3_Update_42 | 1-150300.7.3.2 · SUSE:Linux Enterprise Live Patching 15 SP3 | Package registry (OSV) |
| suse:kernel-obs-build | 5.3.18-150300.59.153.2 · SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS | Package registry (OSV) |
| suse:kernel-preempt | 5.3.18-150300.59.153.2 · SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS | Package registry (OSV) |
| suse:kernel-rt | 5.3.18-150300.161.1 · SUSE:Linux Enterprise Micro 5.1 | Package registry (OSV) |
| suse:kernel-source | 5.3.18-150300.59.153.2 · SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS | Package registry (OSV) |
| suse:kernel-source-rt | 5.3.18-150300.161.1 · SUSE:Linux Enterprise Micro 5.1 | Package registry (OSV) |
| suse:kernel-syms | 5.3.18-150300.59.153.1 · SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS | Package registry (OSV) |
| suse:kernel-zfcpdump | 5.3.18-150300.59.153.2 · SUSE:Linux Enterprise Server 15 SP3-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.
National notice (Türkiye Cybersecurity Directorate / USOM)
Official security notices citing this record; remediation advice is on the agency's page.
- TR-24-0131 · Feb 27, 2024(Linux Kernel Güncellemesi)
Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.
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-476 · NULL Pointer DereferenceCVSS 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 (1)
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (7 more)Show less
- git.kernel.org/stable/c/388d05f70f1ee0cac4a2068fd295072f1a44152a
- git.kernel.org/stable/c/4a2933c88399c0ebc738db39bbce3ae89786d723
- git.kernel.org/stable/c/8a12f8836145ffe37e9c8733dce18c22fb668b66
- git.kernel.org/stable/c/92028d7a31e55d53e41cff679156b9432cffcb36
- git.kernel.org/stable/c/a462067d7c8e6953a733bf5ade8db947b1bb5449
- git.kernel.org/stable/c/caf5ac93b3b5d5fac032fc11fbea680e115421b4
- git.kernel.org/stable/c/dc195928d7e4ec7b5cfc6cd10dc4c8d87a7c72ac
Vendor advisories and official records. Exploit/PoC links are deliberately left out.