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CVE-2025-39822
io_uring/kbuf: fix signedness in this_len calculation
Published 2025-09-16 (13 months ago) by the Linux kernel CNA. Subsystem io_uring. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2025-39822 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| 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 | 6.16.5-1 | Update the kernel and reboot. Fixed in 6.16.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 6.16.5-1 | Update the kernel and reboot. Fixed in 6.16.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
When importing and using buffers, buf->len is considered unsigned. However, buf->len is converted to signed int when committing. This can lead to unexpected behavior if the buffer is large enough to be interpreted as a negative value. Make min_t calculation unsigned.
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.
io_uring/kbuf.c
- What this is
- IO_URINGMAINTAINERS section matched on io_uring/ · io-uring@vger.kernel.org · Maintained
Check it on the machine
grep -w CONFIG_IO_URING /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, sidy
- y
- built into the kernel image on every flavour - only a patch removes it
- Build switch
- CONFIG_IO_URING
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
- 2025-09-16 (13 months ago)source
- CVSS
- no vector published, unrated
- Attack vector
- not published
- EPSS
- 0.13%, higher than 2.4% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- io_uring
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.15 | 6.16.5 | f4f411c06840 |
| 6.15 | 6.17 | c64eff368ac6 |
Why the CNA scored it this way
The kernel CNA published no CVSS vector and no reasoning for CVE-2025-39822, 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.