Summary
In the Linux kernel, the following vulnerability has been resolved: ALSA: timer: fix ida_free...
In the Linux kernel, the following vulnerability has been resolved:
ALSA: timer: fix ida_free call while not allocated
In the snd_utimer_create() function, if the kasprintf() function return
NULL, snd_utimer_put_id() will be called, finally use ida_free()
to free the unallocated id 0.
the syzkaller reported the following information:
------------[ cut here ]------------
ida_free called for id=0 which is not allocated.
WARNING: CPU: 1 PID: 1286 at lib/idr.c:592 ida_free+0x1fd/0x2f0 lib/idr.c:592
Modules linked in:
CPU: 1 UID: 0 PID: 1286 Comm: syz-executor164 Not tainted 6.15.8 #3 PREEMPT(lazy)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-4.fc42 04/01/2014
RIP: 0010:ida_free+0x1fd/0x2f0 lib/idr.c:592
Code: f8 fc 41 83 fc 3e 76 69 e8 70 b2 f8 (...)
RSP: 0018:ffffc900007f79c8 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 1ffff920000fef3b RCX: ffffffff872176a5
RDX: ffff88800369d200 RSI: 0000000000000000 RDI: ffff88800369d200
RBP: 0000000000000000 R08: ffffffff87ba60a5 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000000
FS: 00007f6f1abc1740(0000) GS:ffff8880d76a0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6f1ad7a784 CR3: 000000007a6e2000 CR4: 00000000000006f0
Call Trace:
snd_utimer_put_id sound/core/timer.c:2043 [inline] [snd_timer]
snd_utimer_create+0x59b/0x6a0 sound/core/timer.c:2184 [snd_timer]
snd_utimer_ioctl_create sound/core/timer.c:2202 [inline] [snd_timer]
__snd_timer_user_ioctl.isra.0+0x724/0x1340 sound/core/timer.c:2287 [snd_timer]
snd_timer_user_ioctl+0x75/0xc0 sound/core/timer.c:2298 [snd_timer]
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:907 [inline]
__se_sys_ioctl fs/ioctl.c:893 [inline]
__x64_sys_ioctl+0x198/0x200 fs/ioctl.c:893
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x7b/0x160 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x76/0x7e
[...]
The utimer->id should be set properly before the kasprintf() function,
ensures the snd_utimer_put_id() function will free the allocated id.
Impact
The application dereferences a null pointer, causing a crash. Typical impact: denial of service via crash.
CVE-2025-39765 has a CVSS score of 5.5 (Medium). The vector is requires local access, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2025-39765? CVE-2025-39765 is a medium-severity null pointer dereference vulnerability. No fixed version is listed yet. The application dereferences a null pointer, causing a crash.
- How severe is CVE-2025-39765? CVE-2025-39765 has a CVSS score of 5.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Is there a fix for CVE-2025-39765? No fixed version is listed for CVE-2025-39765 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is CVE-2025-39765 exploitable, and should I be worried? Whether CVE-2025-39765 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-39765 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.