CVE-2026-85769 Libtpms: libtpms: heap out-of-bounds read in tpm2 state unmarshalling via unchecked block_skip_read() blocksize
A heap out-of-bounds read in libtpms allows attackers to crash the TPM emulation process via malformed state blobs, causing denial of service.
- 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-2026-85769?
CVE-2026-85769 is a medium-severity memory corruption vulnerability in Red Hat Enterprise Linux 10, published on 4 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
A flaw was found in libtpms, a library that provides software TPM 2.0 emulation. When restoring TPM 2.0 state (for example during a virtual machine's power-on or state/migration restore), a malformed state blob can supply an oversized skip-block length that is not validated against the remaining size of the input buffer. This can drive an internal size counter negative, which bypasses a subsequent bounds check due to an unsafe signed-to-unsigned conversion, causing the parser to read memory outside the bounds of the heap buffer holding the state data. Successful exploitation can crash the process hosting libtpms (such as swtpm), resulting in a denial of service of the emulated TPM device and the virtual machine that depends on it. No data corruption or information disclosure was confirmed.
Weakness: CWE-125
Which versions are affected by CVE-2026-85769?
Linux distribution packages (4)
libtpms SUSE:Linux Enterprise Module for Server Applications 15 SP7 | All versions | 0.9.6-150600.3.6.1 |
libtpms SUSE:Linux Micro 6.0 | All versions | 0.9.6-3.1 |
libtpms SUSE:Linux Micro 6.1 | All versions | 0.9.6-slfo.1.1_3.1 |
libtpms openSUSE:Tumbleweed | All versions | 0.10.2-2.1 |
How do I fix CVE-2026-85769?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-85769 being exploited?
There is no known exploitation of CVE-2026-85769 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Sources
Also known as AZL-99918, DEBIAN-CVE-2026-85769, GHSA-8pv5-2vvh-f478, SUSE-SU-2026:23878-1, SUSE-SU-2026:23926-1, SUSE-SU-2026:4363-1 and 2 more.