Raw vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:HSummary
CVE-2026-43203 is a high-severity Use After Free (CWE-416) vulnerability in Linux Linux Kernel. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 36th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SI-16 (Memory Protection) and SC-39 (Process Isolation) — see the control section below for these in your framework.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-27764
Vulnerability Data
In the Linux kernel, the following vulnerability has been resolved: atm: fore200e: fix use-after-free in tasklets during device removal When the PCA-200E or SBA-200E adapter is being detached, the fore200e is deallocated. However, the tx_tasklet or rx_tasklet may still be…
more
running or pending, leading to use-after-free bug when the already freed fore200e is accessed again in fore200e_tx_tasklet() or fore200e_rx_tasklet(). One of the race conditions can occur as follows: CPU 0 (cleanup) | CPU 1 (tasklet) fore200e_pca_remove_one() | fore200e_interrupt() fore200e_shutdown() | tasklet_schedule() kfree(fore200e) | fore200e_tx_tasklet() | fore200e-> // UAF Fix this by ensuring tx_tasklet or rx_tasklet is properly canceled before the fore200e is released. Add tasklet_kill() in fore200e_shutdown() to synchronize with any pending or running tasklets. Moreover, since fore200e_reset() could prevent further interrupts or data transfers, the tasklet_kill() should be placed after fore200e_reset() to prevent the tasklet from being rescheduled in fore200e_interrupt(). Finally, it only needs to do tasklet_kill() when the fore200e state is greater than or equal to FORE200E_STATE_IRQ, since tasklets are uninitialized in earlier states. In a word, the tasklet_kill() should be placed in the FORE200E_STATE_IRQ branch within the switch...case structure. This bug was identified through static analysis.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Kernel UAF in driver tasklet handling during device removal directly enables local privilege escalation via exploitation of the race condition.
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
Mitigating Controls (NIST 800-53 r5) AI
Memory protection mechanisms directly block access to freed kernel structures (fore200e) by tasklets after kfree in fore200e_shutdown.
Process isolation confines driver tasklet execution contexts so that pending tx/rx tasklets cannot dereference memory released during device detach.
Integrity verification of kernel modules and drivers can detect the unsafe tasklet scheduling versus kfree race introduced in fore200e_pca_remove_one.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly incorporate memory-safety tooling and reviews that prevent most use-after-free defects.
Vulnerability identification processes can discover use-after-free issues via scanning or analysis but do not prevent their introduction.
Routine patching removes known use-after-free instances after they have been introduced in released software.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development can detect use-after-free bugs before release.
Secure SDLC mandates memory-safety practices that reduce use-after-free defects.
Application security requirements can specify memory-management rules that mitigate use-after-free.
Secure architecture principles include memory-safety design choices that limit use-after-free exposure.
Secure coding standards directly prescribe avoidance of use-after-free patterns.
Change-management processes help ensure memory-safety fixes are deployed consistently.