The Patching Friars' AlmanacA calendar of CVE saints

January 2

ChronomalyHoly card for chronomaly, generated with AI (Claude, Anthropic) for the Lunario dei Frati Patchatori.CC BY-NC-SA 4.0 Chronomaly TEMPUS FUGIT, THREAD QUOQUE
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Saint Chronomaly, Lord of the Timers

Patron of those with a race condition always pending and zombie processes that don't know they're dead.

Life

He lived deep in the Linux kernel, among the POSIX CPU timers. When a process died without being reaped, its timer could still fire while the parent was clearing away the remains: one moment too many, and freed memory came back to life. He was exploited in targeted attacks on Android before the world knew his name, and in early 2026 a researcher told the story of his passion in instalments.

Prayer

O Saint Chronomaly, who dwells in the instant between check and use, grant us locks taken properly and timers cancelled in time. Amen.

How to celebrate

Celebrated by updating the kernel and, by tradition, arriving at every appointment exactly one tick late.

Time waits for no thread, and a racing thread waits for no one.

Technical record

Disclosed on
January 2 2026
CVE
CVE-2025-38352
CVSS
7.8Actively exploited (CISA KEV)
Product
Linux · Linux

In the Linux kernel, the following vulnerability has been resolved: posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del() If an exiting non-autoreaping task has already passed exit_notify() and calls handle_posix_cpu_timers() from IRQ, it can be reaped by its parent or debugger right after unlock_task_sighand(). If a concurrent posix_cpu_timer_del() runs at that moment, it won't be able to detect timer->it.cpu.firing != 0: cpu_timer_task_rcu() and/or lock_task_sighand() will fail. Add the tsk->exit_state check into run_posix_cpu_timers() to fix this. This fix is not needed if CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y, because exit_task_work() is called before exit_notify(). But the check still makes sense, task_work_add(&tsk->posix_cputimers_work.work) will fail anyway in this case.

Sources: faith2dxy.xyz

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