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CVE-2026-98728
tpm: fix off-by-four bounds check in tpm2_get_random()
Published 2026-10-18 (today) by the Linux kernel CNA. Subsystem drivers/char. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-98728 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 | fixed | 6.12.113-1 | Update the kernel and reboot. Fixed in 6.12.113-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.10-1 | Update the kernel and reboot. Fixed in 7.2.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.10-1 | Update the kernel and reboot. Fixed in 7.2.10-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
When the response carries the TPM2_ST_SESSIONS tag, tpm2_get_random() skips the 4-byte parameter size field before locating the random data, but the bounds check still validates the response length against TPM_HEADER_SIZE. A truncated response can pass the check and make memcpy() read up to 4 bytes past the response end, so stale buffer contents end up in the caller's random bytes. Fix this by checking the response length against 'offset', which already includes the skipped parameter size field.
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.
drivers/char/tpm/tpm2-cmd.c
- What this is
- TPM DEVICE DRIVERMAINTAINERS section matched on drivers/char/tpm/ · linux-integrity@vger.kernel.org · Maintained
Check it on the machine
grep -w CONFIG_TCG_TPM /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_TCG_TPM
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
- 2026-10-18 (today)source
- CVSS
- no vector published, unrated
- Attack vector
- not published
- EPSS
- not scored
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/char
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.10 | 6.12.113 | be54101992c2 |
| 6.10 | 6.18.56 | e30a2406408d |
| 6.10 | 7.2.10 | 42bb6216b861 |
| 6.10 | 7.3 | 9b522400bf5c |
Why the CNA scored it this way
The kernel CNA published no CVSS vector and no reasoning for CVE-2026-98728, 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.