CVE-2026-99233
tracing/histograms: Verify event_call identity when updating synth_event refcount
What happened?
In the Linux kernel, the following vulnerability has been resolved:
tracing/histograms: Verify event_call identity when updating synth_event refcount
In event_hist_trigger_parse() and hist_unreg_all(), the histogram registration and unregistration paths look up find_synth_event() using trace_event_name(file->event_call) and adjust se->ref if a match is found.
Because find_synth_event() only compares the event basename, registering or removing a histogram on a non-synthetic trace event whose basename matches a synthetic event erroneously modifies the synthetic event's reference count. If a histogram is registered on the non-synthetic event before the synthetic event is created and removed afterwards, se->ref is decremented without a matching increment, allowing the synthetic event to be freed while an active histogram action still holds a pointer to it.
Introduce find_synth_event_call() to verify that &se->call matches file->event_call before adjusting se->ref.
Affected software and versions
| Software | Version information | Fixed version |
|---|---|---|
| LinuxLinux | affected: 4b147936fa509650beaf638b331573c23ba4d609 to < 381f543ed35c434d5b707369aa5dcd69ecf440af; affected: 4b147936fa509650beaf638b331573c23ba4d609 to < 4472579bd1c83708b6fe623c870cdf728e947205; affected: 4b147936fa509650beaf638b331573c23ba4d609 to < 23b4106e8b35823acc79e206c7745f55b9cfd78b; affected: 4b147936fa509650beaf638b331573c23ba4d609 to < 06e816bed499fe47f39f12044382cc5d064485fb; affected: 4b147936fa509650beaf638b331573c23ba4d609 to < 5597bb8db6855fcb97a67196d227fea359bcd81c; affected: 4b147936fa509650beaf638b331573c23ba4d609 to < cf4e31d5da80fae4c9cdbe7af55b7c3ad213f0e4; affected: 4b147936fa509650beaf638b331573c23ba4d609 to < 3403d9bb27ebc3572bd048620746b4414e073bf9 | See vendor advisory |
| LinuxLinux | affected: 4.17; unaffected: 0 to < 4.17; unaffected: 6.1.191 to ≤ 6.1.*; unaffected: 6.6.161 to ≤ 6.6.*; unaffected: 6.12.115 to ≤ 6.12.*; unaffected: 6.18.60 to ≤ 6.18.*; unaffected: 7.2.14 to ≤ 7.2.*; unaffected: 7.3.1 to ≤ 7.3.*; unaffected: 7.4-rc1 to ≤ * | See vendor advisory |
Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.
Is it being exploited?
This CVE was not listed in the CISA catalogue at our last retrieval. This does not establish that exploitation is absent.
How to respond
- Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
- Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
- Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.
Sources and remediation references
- https://www.cve.org/CVERecord?id=CVE-2026-99233
- https://git.kernel.org/stable/c/381f543ed35c434d5b707369aa5dcd69ecf440af
- https://git.kernel.org/stable/c/4472579bd1c83708b6fe623c870cdf728e947205
- https://git.kernel.org/stable/c/23b4106e8b35823acc79e206c7745f55b9cfd78b
- https://git.kernel.org/stable/c/06e816bed499fe47f39f12044382cc5d064485fb
- https://git.kernel.org/stable/c/5597bb8db6855fcb97a67196d227fea359bcd81c
- https://git.kernel.org/stable/c/cf4e31d5da80fae4c9cdbe7af55b7c3ad213f0e4
- https://git.kernel.org/stable/c/3403d9bb27ebc3572bd048620746b4414e073bf9