# CVE-2025-40028: linux: In the Linux kernel, the following vulnerability has been resolved:  binder: fix double-free in dbitmap  A process mi...

CVE-2025-40028 is fixed in linux on 1 platform, first by DEBIAN-CVE-2025-40028, released October 28, 2025. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2025-40028
- Priority: High
- CVSS: 7.8 (high)
- EPSS: 0.0015
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 28, 2025

## Description

In the Linux kernel, the following vulnerability has been resolved:  binder: fix double-free in dbitmap  A process might fail to allocate a new bitmap when trying to expand its proc->dmap. In that case, dbitmap_grow() fails and frees the old bitmap via dbitmap_free(). However, the driver calls dbitmap_free() again when the same process terminates, leading to a double-free error:    ==================================================================   BUG: KASAN: double-free in binder_proc_dec_tmpref+0x2e0/0x55c   Free of addr ffff00000b7c1420 by task kworker/9:1/209    CPU: 9 UID: 0 PID: 209 Comm: kworker/9:1 Not tainted 6.17.0-rc6-dirty #5 PREEMPT   Hardware name: linux,dummy-virt (DT)   Workqueue: events binder_deferred_func   Call trace:    kfree+0x164/0x31c    binder_proc_dec_tmpref+0x2e0/0x55c    binder_deferred_func+0xc24/0x1120    process_one_work+0x520/0xba4   [...]    Allocated by task 448:    __kmalloc_noprof+0x178/0x3c0    bitmap_zalloc+0x24/0x30    binder_open+0x14c/0xc10   [...]    Freed by task 449:    kfree+0x184/0x31c    binder_inc_ref_for_node+0xb44/0xe44    binder_transaction+0x29b4/0x7fbc    binder_thread_write+0x1708/0x442c    binder_ioctl+0x1b50/0x2900   [...]   ==================================================================  Fix this issue by marking proc->map NULL in dbitmap_free().

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.57-1 | [DEBIAN-CVE-2025-40028](https://patchblox.com/security/data/fix/linux/debian-cve-2025-40028.md) | Oct 28, 2025 |
| Linux | linux Debian 14 | 6.17.6-1 | [DEBIAN-CVE-2025-40028](https://patchblox.com/security/data/fix/linux/debian-cve-2025-40028.md) | Oct 28, 2025 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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