CVE-2026-68090
debugobjects: Plug race against a concurrent OOM disable
Published Aug 10, 2026
CVSS 3.1 · 5.5 Medium
EPSS < 1%
KEV · Not listed
Description
In the Linux kernel, the following vulnerability has been resolved:
debugobjects: Plug race against a concurrent OOM disable
syzbot reported a puzzling splat:
WARNING: kernel/time/hrtimer.c:443 at stub_timer+0xa/0x20
stub_timer() is installed as timer callback function in
hrtimer_fixup_assert_init(), which is invoked when
debug_object_assert_init() can't find a shadow object. In that case debug
objects emits a warning about it before invoking the fixup.
Though the provided console log lacks this warning and instead has the
following a few seconds before the splat:
ODEBUG: Out of memory. ODEBUG disabled
So the object was looked up in debug_object_assert_init() and the lookup
failed due a concurrent out of memory situation which disabled debug
objects and freed the shadow objects:
debug_object_assert_init()
if (!debug_objects_enabled)
return; obj = alloc();
if (!obj) {
// Out of memory
debug_objects_enabled = false;
free_objects();
obj = lookup_or_alloc();
// The lookup failed because the other side
// removed the objects, so this returns
// an error code as the object in question
// is not statically initialized
if (!IS_ERR_OR_NULL(obj))
return;
if (!obj) {
debug_oom();
return;
}
print(...)
if (!debug_objects_enabled)
return;
fixup(...)
The debug object splat is skipped because debug_objects_enabled is false,
but the fixup callback is invoked unconditionally, which makes the timer
disfunctional.
This is only a problem in debug_object_assert_init() and
debug_object_activate() as both have to handle statically initialized
objects and therefore must handle the error pointer return case
gracefully. All other places only handle the found/not found case and the
NULL pointer return is a signal for OOM. Otherwise they get a valid shadow
object.
Plug the hole by checking whether debug objects are still enabled before
invoking the print and fixup function in those two places.
debugobjects: Plug race against a concurrent OOM disable
syzbot reported a puzzling splat:
WARNING: kernel/time/hrtimer.c:443 at stub_timer+0xa/0x20
stub_timer() is installed as timer callback function in
hrtimer_fixup_assert_init(), which is invoked when
debug_object_assert_init() can't find a shadow object. In that case debug
objects emits a warning about it before invoking the fixup.
Though the provided console log lacks this warning and instead has the
following a few seconds before the splat:
ODEBUG: Out of memory. ODEBUG disabled
So the object was looked up in debug_object_assert_init() and the lookup
failed due a concurrent out of memory situation which disabled debug
objects and freed the shadow objects:
debug_object_assert_init()
if (!debug_objects_enabled)
return; obj = alloc();
if (!obj) {
// Out of memory
debug_objects_enabled = false;
free_objects();
obj = lookup_or_alloc();
// The lookup failed because the other side
// removed the objects, so this returns
// an error code as the object in question
// is not statically initialized
if (!IS_ERR_OR_NULL(obj))
return;
if (!obj) {
debug_oom();
return;
}
print(...)
if (!debug_objects_enabled)
return;
fixup(...)
The debug object splat is skipped because debug_objects_enabled is false,
but the fixup callback is invoked unconditionally, which makes the timer
disfunctional.
This is only a problem in debug_object_assert_init() and
debug_object_activate() as both have to handle statically initialized
objects and therefore must handle the error pointer return case
gracefully. All other places only handle the found/not found case and the
NULL pointer return is a signal for OOM. Otherwise they get a valid shadow
object.
Plug the hole by checking whether debug objects are still enabled before
invoking the print and fixup function in those two places.
Affected Products
-
CVE record
-
NVD configurations
No data
-
Red Hat packages
No data
-
OpenCVE enrichment
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
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| Linux | Linux | affected |
|
No data.
No data.
| Vendor | Product | Versions | ||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Kernel |
|
||||||||||||||||||||||||||||||||||||||||||||
| Linux | Kernel |
|
Remediation
Tracking
Advisories
| Source | ID | Title |
|---|---|---|
 Ubuntu USN |
USN-8726-1 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-8727-1 | Linux kernel (OEM) vulnerabilities |
| Ubuntu USN |
USN-8728-1 | Linux kernel (GCP) vulnerabilities |
| Ubuntu USN |
USN-8760-1 | Linux kernel (NVIDIA) vulnerabilities |
| Ubuntu USN |
USN-8726-2 | Linux kernel (Raspberry Pi) vulnerabilities |
| Ubuntu USN |
USN-8726-3 | Linux kernel (IBM) vulnerabilities |
| Ubuntu USN |
USN-8800-1 | Linux kernel (NVIDIA BaseOS) vulnerabilities |
| Ubuntu USN |
USN-8760-2 | Linux kernel (NVIDIA) vulnerabilities |
| Ubuntu USN |
USN-8726-4 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-8728-2 | Linux kernel (Azure) vulnerabilities |
| Ubuntu USN |
USN-8728-3 | Linux kernel (Oracle) vulnerabilities |
| Ubuntu USN |
USN-8876-1 | Linux kernel (Azure CVM) vulnerabilities |
| Ubuntu USN |
USN-8875-1 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-8877-1 | Linux kernel (GCP) vulnerabilities |
| Ubuntu USN |
USN-8878-1 | Linux kernel (GCP) vulnerabilities |
| Ubuntu USN |
USN-8879-1 | Linux kernel (Oracle) vulnerabilities |
| Ubuntu USN |
USN-8875-2 | Linux kernel (NVIDIA) vulnerabilities |
| Ubuntu USN |
USN-8917-1 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-8918-1 | Linux kernel (Azure) vulnerabilities |
| Ubuntu USN |
USN-9024-1 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-9025-1 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-9026-1 | Linux kernel (Azure) vulnerabilities |
| Ubuntu USN |
USN-9029-1 | Linux kernel (Raspberry Pi) vulnerabilities |
| Ubuntu USN |
USN-9040-1 | Linux kernel (Low Latency NVIDIA) vulnerabilities |
| Ubuntu USN |
USN-9066-1 | Linux kernel (HWE) vulnerabilities |
| Ubuntu USN |
USN-9091-1 | Linux kernel (NVIDIA Tegra) vulnerabilities |
Metrics
No CVSS v4.0
Attack Vector Local
Attack Complexity Low
Privileges Required Low
Scope Unchanged
Confidentiality Impact None
Integrity Impact None
Availability Impact High
User Interaction None
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.177% probability within 30 days)
Key SSVC decision points have not yet been added.
References
History
Aug 13, 2026 9:15 AM
Weaknesses updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-469 |
Aug 12, 2026 12:15 AM
Weaknesses updated. Added references. Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-367 | |
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Aug 11, 2026 3:30 AM
First appearance in the feed. Affected vendors updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Linux kernel
|
|
| Vendors & Products |
Linux kernel
|
Aug 10, 2026 8:15 PM
Weaknesses updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-469 |
Aug 10, 2026 12:00 PM
Description updated. Title updated. First appearance in the feed. Affected versions updated. Affected vendors updated. Added references
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: debugobjects: Plug race against a concurrent OOM disable syzbot reported a puzzling splat: WARNING: kernel/time/hrtimer.c:443 at stub_timer+0xa/0x20 stub_timer() is installed as timer callback function in hrtimer_fixup_assert_init(), which is invoked when debug_object_assert_init() can't find a shadow object. In that case debug objects emits a warning about it before invoking the fixup. Though the provided console log lacks this warning and instead has the following a few seconds before the splat: ODEBUG: Out of memory. ODEBUG disabled So the object was looked up in debug_object_assert_init() and the lookup failed due a concurrent out of memory situation which disabled debug objects and freed the shadow objects: debug_object_assert_init() if (!debug_objects_enabled) return; obj = alloc(); if (!obj) { // Out of memory debug_objects_enabled = false; free_objects(); obj = lookup_or_alloc(); // The lookup failed because the other side // removed the objects, so this returns // an error code as the object in question // is not statically initialized if (!IS_ERR_OR_NULL(obj)) return; if (!obj) { debug_oom(); return; } print(...) if (!debug_objects_enabled) return; fixup(...) The debug object splat is skipped because debug_objects_enabled is false, but the fixup callback is invoked unconditionally, which makes the timer disfunctional. This is only a problem in debug_object_assert_init() and debug_object_activate() as both have to handle statically initialized objects and therefore must handle the error pointer return case gracefully. All other places only handle the found/not found case and the NULL pointer return is a signal for OOM. Otherwise they get a valid shadow object. Plug the hole by checking whether debug objects are still enabled before invoking the print and fixup function in those two places. | |
| Title | debugobjects: Plug race against a concurrent OOM disable | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
Weaknesses
