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.
Published: 2026-09-04
Score: 6.5 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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Remediation

Vendor Workaround

No mitigation is currently available that meets Red Hat Product Security's standards for usability, deployment, applicability, or stability.

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History

Fri, 04 Sep 2026 18:00:00 +0000

Type Values Removed Values Added
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.
Title Libtpms: libtpms: heap out-of-bounds read in tpm2 state unmarshalling via unchecked block_skip_read() blocksize
First Time appeared Redhat
Redhat enterprise Linux
Weaknesses CWE-125
CPEs cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


Subscriptions

Redhat Enterprise Linux
cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-09-04T18:51:12.453Z

Reserved: 2026-09-04T15:19:09.987Z

Link: CVE-2026-85769

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-04T18:18:07.153

Modified: 2026-09-04T19:17:34.020

Link: CVE-2026-85769

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-04T20:15:14Z

Weaknesses