CVE-2026-98728 tpm: fix off-by-four bounds check in tpm2_get_random()
A local attacker can read stale kernel memory via a truncated TPM response, potentially leaking sensitive data.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98728?
CVE-2026-98728 is a vulnerability in Linux, published on 18 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
tpm: fix off-by-four bounds check in tpm2_get_random()
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.
Which versions are affected by CVE-2026-98728?
How do I fix CVE-2026-98728?
Apply the vendor's patch.
Is CVE-2026-98728 being exploited?
There is no known exploitation of CVE-2026-98728 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-98728, DEBIAN-CVE-2026-98728, GHSA-m4p2-cqr5-x7cx, UBUNTU-CVE-2026-98728.