Revert "tty: n_gsm: fix UAF in gsm_cleanup_mux"
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
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-476.
Summary
In the Linux kernel, the following vulnerability has been resolved: Revert "tty: n_gsm: fix UAF in gsm_cleanup_mux" This reverts commit 9b9c8195f3f0d74a826077fc1c01b9ee74907239. The commit above is reverted as it did not solve the original issue. gsm_cleanup_mux() tries to free up the virtual ttys by calling gsm_dlci_release() for each available DLCI. There, dlci_put() is called to decrease the reference counter for the DLCI via tty_port_put() which finally calls gsm_dlci_free(). This already clears the pointer which is being checked in gsm_cleanup_mux() before calling gsm_dlci_release(). Therefore, it is not necessary to clear this pointer in gsm_cleanup_mux() as done in the reverted commit. The commit introduces a null pointer dereference: <TASK> ? __die+0x1f/0x70 ? page_fault_oops+0x156/0x420 ? search_exception_tables+0x37/0x50 ? fixup_exception+0x21/0x310 ? exc_page_fault+0x69/0x150 ? asm_exc_page_fault+0x26/0x30 ? tty_port_put+0x19/0xa0 gsmtty_cleanup+0x29/0x80 [n_gsm] release_one_tty+0x37/0xe0 process_one_work+0x1e6/0x3e0 worker_thread+0x4c/0x3d0 ? __pfx_worker_thread+0x10/0x10 kthread+0xe1/0x110 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x2f/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1b/0x30 </TASK> The actual issue is that nothing guards dlci_put() from being called multiple times while the tty driver was triggered but did not yet finished calling gsm_dlci_free().
Why it matters now
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 | 5.10.190 to before 5.10.198; 5.15.124 to before 5.15.134; 6.1.43 to before 6.1.56; 6.4.8 to before 6.5 | 5.10.198, 5.15.134, 6.1.56, 6.5 | Patch available | CNA |
| Linux | Linux | 6.5 and later | 5.10.198, 5.15.134, 6.1.56, 6.5.6, 6.6 | Patch available | CNA |
- Linux VendorLinux Affected 5.10.190 to before 5.10.198; 5.15.124 to before 5.15.134; 6.1.43 to before 6.1.56; 6.4.8 to before 6.5 Fixed in 5.10.198, 5.15.134, 6.1.56, 6.5 Patch available CNA
- Linux VendorLinux Affected 6.5 and later Fixed in 5.10.198, 5.15.134, 6.1.56, 6.5.6, 6.6 Patch available CNA
CPE configurations NVD · 4
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | 5.10.190 to before 5.10.198; 5.15.124 to before 5.15.134; 6.1.43 to before 6.1.56; 6.5 to before 6.5.6 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:6.6:rc1:*:*:*:*:*:* | 6.6 rc1 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:6.6:rc2:*:*:*:*:*:* | 6.6 rc2 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:6.6:rc3:*:*:*:*:*:* | 6.6 rc3 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 5.10.190 to before 5.10.198; 5.15.124 to before 5.15.134; 6.1.43 to before 6.1.56; 6.5 to before 6.5.6 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:6.6:rc1:*:*:*:*:*:* Versions 6.6 rc1 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:6.6:rc2:*:*:*:*:*:* Versions 6.6 rc2 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:6.6:rc3:*:*:*:*:*:* Versions 6.6 rc3 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 5.10.198, 5.15.134, 6.1.56, 6.5
- Fix · CNA Linux (Linux) Fixed in 5.10.198, 5.15.134, 6.1.56, 6.5.6, 6.6
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
Not affected: 4 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2023-52564
- 2026-10-03 Alias added: GHSA-g7pr-gf5r-fx64
References
Patch 5
- https://git.kernel.org/stable/c/6d5c8862932d31a810b6545f7d69ecc124402c6e
- https://git.kernel.org/stable/c/a48d2bcd23f2c98d575bc2f9b7a3fbd16aeea9eb
- https://git.kernel.org/stable/c/c61d0b87a7028c2c10faffc524d748334c7b9827
- https://git.kernel.org/stable/c/2bff660e0ff349dee84dc4f6f6d10da4497f5b28
- https://git.kernel.org/stable/c/29346e217b8ab8a52889b88f00b268278d6b7668
More Linux Kernel vulnerabilities
- TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
- TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
- TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
- TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
- TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
- TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
Sources
- CVE-2023-52564 · CVE Program
- CVE-2023-52564 · NVD
- FIRST EPSS
- GHSA-g7pr-gf5r-fx64 · GitHub Advisory Database · CC BY 4.0
- CVE-2023-52564 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences