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CVE-2026-89765
timers/itimer: Zero-init old itimerval before copy to userspace
Published 2026-09-11 (37 days ago) by the Linux kernel CNA. Subsystem kernel/time. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-89765 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 | fixedDLA-4841-1 · 2026-10-17 · text | 6.1.190-1 | Update the kernel and reboot. DLA-4841-1 shipped the fix on 2026-10-17, in 6.1.190-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
On native sparc64, struct __kernel_old_timeval contains a four-byte hole after tv_usec because tv_sec is 64-bit while __kernel_suseconds_t is 32-bit. put_itimerval() fills only the named fields in a stack-allocated __kernel_old_itimerval and copies the entire object to userspace, so getitimer() can expose the two padding holes. Zero-initialize the aggregate before assigning the fields so implicit padding is deterministic before it crosses the user/kernel boundary.
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.
kernel/time/itimer.c
- What this is
- POSIX CLOCKS and TIMERSMAINTAINERS section matched on kernel/time/itimer.c · linux-kernel@vger.kernel.org · Maintained
Check it on the machine
grep -w CONFIG_POSIX_TIMERS /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
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, sid, bookworm · linux-6.12y
- y
- built into the kernel image on every flavour - only a patch removes it
- Build switch
- CONFIG_POSIX_TIMERS
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 kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-09-11 (37 days ago)source
- CVSS
- no vector published, unrated
- Attack vector
- not published
- EPSS
- 0.20%, higher than 9.4% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- kernel/time
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.12 | 5.10.270 | 6d4b93725138 |
| 2.6.12 | 5.15.221 | 4ea70146ab93 |
| 2.6.12 | 6.1.188 | a17b345daff4 |
| 2.6.12 | 6.6.157 | bdfda99c5763 |
| 2.6.12 | 6.12.109 | 4c66719dd1e4 |
| 2.6.12 | 6.18.50 | 2bf5e8f7c9bf |
| 2.6.12 | 7.2.4 | 00ef529a5402 |
| 2.6.12 | 7.3 | 18c7d85864e5 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | tracker |
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | tracker |
Why the CNA scored it this way
The kernel CNA published no CVSS vector and no reasoning for CVE-2026-89765, 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.