CVE-2024-56739 rtc: check if __rtc_read_time was successful in rtc_timer_do_work()

What is CVE-2024-56739?

CVE-2024-56739 is a medium-severity denial of service vulnerability in Linux kernel, published on 29 Dec 2024. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

rtc: check if __rtc_read_time was successful in rtc_timer_do_work()

If the __rtc_read_time call fails,, the struct rtc_time tm; may contain uninitialized data, or an illegal date/time read from the RTC hardware.

When calling rtc_tm_to_ktime later, the result may be a very large value (possibly KTIME_MAX). If there are periodic timers in rtc->timerqueue, they will continually expire, may causing kernel softlockup.

Weakness: CWE-908

Which versions are affected by CVE-2024-56739?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2024-56739?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2024-56739 being exploited?

There is no known exploitation of CVE-2024-56739 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-55041, AZL-55076, BELL-CVE-2024-56739, DEBIAN-CVE-2024-56739, GHSA-42wq-32p9-mf48, UBUNTU-CVE-2024-56739.