CVE-2026-99235
In the Linux kernel, the following vulnerability has been resolved:
tracing: Save the event file instead of the compatible histogram
create_field_var_hist() creates a histogram on the matched event to supply a field variable, and records it on the target so it can be torn down later:
hist_data = find_compatible_hist(target_hist_data, file);
...
/* Save the compatible histogram information */
var_hist->hist_data = hist_data;
hist_data is not the histogram it creates. It is one that was already there, whose keys the new one copies. The saved pointer has a single user, unregister_field_var_hists(), which runs when the target is removed:
file = hist_data->field_var_hists[i]->hist_data->event_file;
find_compatible_hist() matches on keys alone, so it can pick one with no variables of its own. check_var_refs() then returns false and the user can remove it while the target still points at it:
BUG: KASAN: slab-use-after-free in event_hist_trigger_free+0x2b2/0x320 Read of size 8 at addr ffff8880093b90e0 by task init/1
Freed by task 1: kfree+0x154/0x420 event_hist_trigger_free+0x1d5/0x320 event_hist_trigger_parse+0x35f3/0x69e0 trigger_process_regex+0x1a6/0x250
Save the event file instead. It is all the dereference ever wanted, and it does not go away when the user removes a trigger.
No affected software listed.
- https://git.kernel.org/stable/c/173914501b97236d7ea7dc2af7f30feddd4e1436
- https://git.kernel.org/stable/c/3609ada3c12cecfb0ae5ee82ef4f86c5f18a2dea
- https://git.kernel.org/stable/c/7a111ba0d1b74c99bc8f096565dc71945f694254
- https://git.kernel.org/stable/c/7cafc82e6153f05a221be678cd649d02e06ba909
- https://git.kernel.org/stable/c/8b307d64a60548e4a74cb746f74d7ed4bd49965e
- https://git.kernel.org/stable/c/9631dbccd3c649b567a5aafffea6b00634183997
- https://git.kernel.org/stable/c/a6165126b1a1b26342b55be6eb6ee23af8756aba
- https://git.kernel.org/stable/c/ac815a379644b2ad5008a009a3516ada31b5dd82
- https://git.kernel.org/stable/c/d5c42664fc094899af9aae5300b27fe8fdb658ef
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A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
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