net: hso: fix NULL-deref on disconnect regression
Priority LOW 24CWE-476Published · Updated
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Partial Red Hat: 4 fixed, 2 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-476.
Summary
In the Linux kernel, the following vulnerability has been resolved: net: hso: fix NULL-deref on disconnect regression Commit 8a12f8836145 ("net: hso: fix null-ptr-deref during tty device unregistration") fixed the racy minor allocation reported by syzbot, but introduced an unconditional NULL-pointer dereference on every disconnect instead. Specifically, the serial device table must no longer be accessed after the minor has been released by hso_serial_tty_unregister().
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00261 17th percentileScored 2026-11-07
Fix Partial Linux (Linux): 4.19.189, 5.4.115, 5.10.33 +3Red Hat: 2 advisoriesRed Hat: 4 fixed, 2 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 4.19.187 to before 4.19.189; 5.4.112 to before 5.4.115; 5.10.30 to before 5.10.33; 5.11.14 to before 5.11.17 | 4.19.189, 5.4.115, 5.10.33, 5.11.17 | Patch available | CNA |
| Linux | Linux | 5.12 and later | 4.19.189, 5.4.115, 5.10.33, 5.11.17, 5.12.1, 5.13 | Patch available | CNA |
- Linux VendorLinux Affected 4.19.187 to before 4.19.189; 5.4.112 to before 5.4.115; 5.10.30 to before 5.10.33; 5.11.14 to before 5.11.17 Fixed in 4.19.189, 5.4.115, 5.10.33, 5.11.17 Patch available CNA
- Linux VendorLinux Affected 5.12 and later Fixed in 4.19.189, 5.4.115, 5.10.33, 5.11.17, 5.12.1, 5.13 Patch available CNA
CPE configurations NVD · 9
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | before 4.19.189; 4.20.0 to before 5.4.115; 5.5.0 to before 5.10.33; 5.11.0 to before 5.11.17 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:5.12:-:*:*:*:*:*:* | 5.12 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:5.12:rc1:*:*:*:*:*:* | 5.12 rc1 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:5.12:rc2:*:*:*:*:*:* | 5.12 rc2 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:5.12:rc3:*:*:*:*:*:* | 5.12 rc3 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:5.12:rc4:*:*:*:*:*:* | 5.12 rc4 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:5.12:rc5:*:*:*:*:*:* | 5.12 rc5 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:5.12:rc6:*:*:*:*:*:* | 5.12 rc6 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:5.12:rc7:*:*:*:*:*:* | 5.12 rc7 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions before 4.19.189; 4.20.0 to before 5.4.115; 5.5.0 to before 5.10.33; 5.11.0 to before 5.11.17 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:5.12:-:*:*:*:*:*:* Versions 5.12 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:5.12:rc1:*:*:*:*:*:* Versions 5.12 rc1 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:5.12:rc2:*:*:*:*:*:* Versions 5.12 rc2 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:5.12:rc3:*:*:*:*:*:* Versions 5.12 rc3 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:5.12:rc4:*:*:*:*:*:* Versions 5.12 rc4 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:5.12:rc5:*:*:*:*:*:* Versions 5.12 rc5 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:5.12:rc6:*:*:*:*:*:* Versions 5.12 rc6 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:5.12:rc7:*:*:*:*:*:* Versions 5.12 rc7 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 4.19.189, 5.4.115, 5.10.33, 5.11.17
- Fix · CNA Linux (Linux) Fixed in 4.19.189, 5.4.115, 5.10.33, 5.11.17, 5.12.1, 5.13
Red Hat 2 advisories
- RHSA-2021:4356 Released 2021-11-09 · Red Hat rating Moderatekernel security, bug fix, and enhancement update
- Red Hat CodeReady Linux Builder (v. 8) kernel-tools-libs-devel-4.18.0-348.el8
- Red Hat Enterprise Linux BaseOS (v. 8) bpftool-4.18.0-348.el8, kernel-4.18.0-348.el8, kernel-abi-stablelists-4.18.0-348.el8 +19
- RHSA-2021:4140 Released 2021-11-09 · Red Hat rating Moderatekernel-rt security and bug fix update
- Red Hat Enterprise Linux Real Time (v. 8) kernel-rt-4.18.0-348.rt7.130.el8, kernel-rt-core-4.18.0-348.rt7.130.el8, kernel-rt-debug-4.18.0-348.rt7.130.el8 +7
- Red Hat Enterprise Linux Real Time for NFV (v. 8) kernel-rt-4.18.0-348.rt7.130.el8, kernel-rt-core-4.18.0-348.rt7.130.el8, kernel-rt-debug-4.18.0-348.rt7.130.el8 +9
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | Affected | No fix planned: Out of support scope |
| Red Hat CodeReady Linux Builder (v. 8) | Fixed | RHSA-2021:4356 |
| Red Hat Enterprise Linux BaseOS (v. 8) | Fixed | RHSA-2021:4356 |
| Red Hat Enterprise Linux Real Time (v. 8) | Fixed | RHSA-2021:4140 |
| Red Hat Enterprise Linux Real Time for NFV (v. 8) | Fixed | RHSA-2021:4140 |
Not affected: 1 product
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2021-46905
- 2026-10-03 Alias added: GHSA-q52q-f54c-xmvp
References
Patch 9
- https://git.kernel.org/stable/c/5871761c5f0f20d6e98bf3b6bd7486d857589554
- https://git.kernel.org/stable/c/0c71d4c89559f72cec2592d078681a843bce570e
- https://git.kernel.org/stable/c/24b699bea7553fc0b98dad9d864befb6005ac7f1
- https://git.kernel.org/stable/c/5c17cfe155d21954b4c7e2a78fa771cebcd86725
- https://git.kernel.org/stable/c/d7fad2ce15bdbbd0fec3ebe999fd7cab2267f53e
- https://git.kernel.org/stable/c/90642ee9eb581a13569b1c0bd57e85d962215273
- https://git.kernel.org/stable/c/0f000005da31f6947f843ce6b3e3a960540c6e00
- https://git.kernel.org/stable/c/41c44e1f3112d7265dae522c026399b2a42d19ef
- https://git.kernel.org/stable/c/2ad5692db72874f02b9ad551d26345437ea4f7f3
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Sources
- CVE-2021-46905 · CVE Program
- CVE-2021-46905 · NVD
- FIRST EPSS
- GHSA-q52q-f54c-xmvp · GitHub Advisory Database · CC BY 4.0
- CVE-2021-46905 · Red Hat security data · CC BY 4.0
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