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CVE-2025-37880
um: work around sched_yield not yielding in time-travel mode
Published 2025-05-09 (17 months ago) by the Linux kernel CNA. Subsystem arch/um. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2025-37880 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | vulnerable | 6.12.113-1 | No fix published anywhere yet, neither in Debian nor upstream for the series trixie tracks. Watch the Debian tracker page for this CVE. Advisories for trixie have historically landed a median of 11 days after publication. |
| Debian 14forky | fixed | 6.16.3-1 | Update the kernel and reboot. Fixed in 6.16.3-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 6.16.3-1 | Update the kernel and reboot. Fixed in 6.16.3-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
sched_yield by a userspace may not actually cause scheduling in time-travel mode as no time has passed. In the case seen it appears to be a badly implemented userspace spinlock in ASAN. Unfortunately, with time-travel it causes an extreme slowdown or even deadlock depending on the kernel configuration (CONFIG_UML_MAX_USERSPACE_ITERATIONS). Work around it by accounting time to the process whenever it executes a sched_yield syscall.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
arch/um/include/linux/time-internal.h
arch/um/kernel/skas/syscall.c
- What this is
- USER-MODE LINUX (UML)MAINTAINERS section matched on arch/um/ · linux-um@lists.infradead.org · Maintained
Show whether Debian builds this, per release
Debian builds this code. Every release below compiles the affected file into the kernels it ships.
- bookworm, trixie, forky, sidy
- y
- built into the kernel image on every flavour - only a patch removes it
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS Debian linux-config packages
Signals
- Published
- 2025-05-09 (17 months ago)source
- CVSS
- no vector published, unrated
- Attack vector
- not published
- EPSS
- 0.18%, higher than 7.0% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- arch/um
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.3 | 6.14.5 | 990ddc651737 |
| 5.3 | 6.15 | 887c5c12e80c |
Why the CNA scored it this way
The kernel CNA published no CVSS vector and no reasoning for CVE-2025-37880, which is why it is shown as unrated rather than given an invented score. 6,405 of the 20,413 CVEs here carry reasoning; this is not one of them.