UBUNTU-CVE-2026-31741
In the Linux kernel, the following vulnerability has been resolved: counter: rz-mtu3-cnt: prevent counter from being toggled multiple times Runtime PM counter is incremented / decremented each time the sysfs enable file is written to. If user writes 0 to the sysfs enable file multiple times, runtime PM usage count underflows, generating the following message. rz-mtu3-counter rz-mtu3-counter.0: Runtime PM usage count underflow! At the same time, hardware registers end up being accessed with clocks off in rz_mtu3_terminate_counter() to disable an already disabled channel. If user writes 1 to the sysfs enable file multiple times, runtime PM usage count will be incremented each time, requiring the same number of 0 writes to get it back to 0. If user writes 0 to the sysfs enable file while PWM is in progress, PWM is stopped without counter being the owner of the underlying MTU3 channel. Check against the cached count_is_enabled value and exit if the user is trying to set the same enable value.
02 / AFFECTED SOFTWARE
Affected packages
6 explicit affected versions
50 explicit affected versions
6 explicit affected versions
10 explicit affected versions
12 explicit affected versions
27 explicit affected versions
34 explicit affected versions
5 explicit affected versions
8 explicit affected versions
10 explicit affected versions
7 explicit affected versions
43 explicit affected versions
13 explicit affected versions
26 explicit affected versions
11 explicit affected versions
20 explicit affected versions
10 explicit affected versions
14 explicit affected versions
12 explicit affected versions
19 explicit affected versions
10 explicit affected versions
6 explicit affected versions
24 explicit affected versions
37 explicit affected versions
26 explicit affected versions
7 explicit affected versions
40 explicit affected versions
13 explicit affected versions
44 explicit affected versions
35 explicit affected versions
18 explicit affected versions
45 explicit affected versions
13 explicit affected versions
4 explicit affected versions
23 explicit affected versions
12 explicit affected versions
52 explicit affected versions
1 explicit affected versions
21 explicit affected versions
7 explicit affected versions
16 explicit affected versions
10 explicit affected versions
10 explicit affected versions
48 explicit affected versions
8 explicit affected versions
7 explicit affected versions
12 explicit affected versions
11 explicit affected versions
7 explicit affected versions
14 explicit affected versions
10 explicit affected versions
1 explicit affected versions
7 explicit affected versions
17 explicit affected versions
12 explicit affected versions
41 explicit affected versions
16 explicit affected versions
17 explicit affected versions
10 explicit affected versions
37 explicit affected versions
10 explicit affected versions
11 explicit affected versions
13 explicit affected versions
10 explicit affected versions
39 explicit affected versions
3 explicit affected versions
10 explicit affected versions
11 explicit affected versions
26 explicit affected versions
10 explicit affected versions
20 explicit affected versions
13 explicit affected versions
29 explicit affected versions
13 explicit affected versions
12 explicit affected versions
41 explicit affected versions
40 explicit affected versions
8 explicit affected versions
33 explicit affected versions
23 explicit affected versions
19 explicit affected versions
11 explicit affected versions
5 explicit affected versions
12 explicit affected versions
11 explicit affected versions
7 explicit affected versions
12 explicit affected versions
10 explicit affected versions
16 explicit affected versions
5 explicit affected versions
10 explicit affected versions
26 explicit affected versions
39 explicit affected versions
35 explicit affected versions
48 explicit affected versions
11 explicit affected versions
10 explicit affected versions
13 explicit affected versions
46 explicit affected versions
16 explicit affected versions
50 explicit affected versions
3 explicit affected versions
7 explicit affected versions
15 explicit affected versions
51 explicit affected versions
16 explicit affected versions
18 explicit affected versions
43 explicit affected versions
12 explicit affected versions
7 explicit affected versions
27 explicit affected versions
43 explicit affected versions
8 explicit affected versions
46 explicit affected versions
13 explicit affected versions
13 explicit affected versions
7 explicit affected versions
8 explicit affected versions
12 explicit affected versions
9 explicit affected versions
44 explicit affected versions
16 explicit affected versions
3 explicit affected versions
18 explicit affected versions
45 explicit affected versions
37 explicit affected versions
50 explicit affected versions
14 explicit affected versions
38 explicit affected versions
9 explicit affected versions
17 explicit affected versions
11 explicit affected versions
39 explicit affected versions
6 explicit affected versions
7 explicit affected versions
4 explicit affected versions
10 explicit affected versions
1 explicit affected versions
13 explicit affected versions
16 explicit affected versions
10 explicit affected versions
8 explicit affected versions
45 explicit affected versions
14 explicit affected versions
4 explicit affected versions
78 explicit affected versions
14 explicit affected versions
11 explicit affected versions
1 explicit affected versions
19 explicit affected versions
1 explicit affected versions
39 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
In the Linux kernel, the following vulnerability has been resolved: counter: rz-mtu3-cnt: prevent counter from being toggled multiple times Runtime PM counter is incremented / decremented each time the sysfs enable file is written to. If user writes 0 to the sysfs enable file multiple times, runtime PM usage count underflows, generating the following message. rz-mtu3-counter rz-mtu3-counter.0: Runtime PM usage count underflow! At the same time, hardware registers end up being accessed with clocks off in rz_mtu3_terminate_counter() to disable an already disabled channel. If user writes 1 to the sysfs enable file multiple times, runtime PM usage count will be incremented each time, requiring the same number of 0 writes to get it back to 0. If user writes 0 to the sysfs enable file while PWM is in progress, PWM is stopped without counter being the owner of the underlying MTU3 channel. Check against the cached count_is_enabled value and exit if the user is trying to set the same enable value.
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/67c3f99bed6f422ba343d2b70a2eeeccdfd91bef
- https://ubuntu.com/security/CVE-2026-31741
- https://ubuntu.com/security/notices/USN-8567-1
- https://ubuntu.com/security/notices/USN-8574-1
- https://ubuntu.com/security/notices/USN-8574-2
- https://ubuntu.com/security/notices/USN-8574-3
- https://ubuntu.com/security/notices/USN-8595-1
- https://ubuntu.com/security/notices/USN-8595-2
- https://ubuntu.com/security/notices/USN-8595-3
- https://ubuntu.com/security/notices/USN-8596-1
- https://ubuntu.com/security/notices/USN-8606-1
- https://ubuntu.com/security/notices/USN-8607-1
- https://ubuntu.com/security/notices/USN-8608-1
- https://ubuntu.com/security/notices/USN-8609-1
- https://ubuntu.com/security/notices/USN-8619-1
- https://www.cve.org/CVERecord?id=CVE-2026-31741