---
id: CVE-2026-75900
title: >-
  Swtpm: swtpm: out-of-bounds read in swtpm_nvram_checkheader due to
  sizeof(pointer) vs sizeof(struct) mismatch
summary: >-
  An out-of-bounds read vulnerability was found in swtpm's
  SWTPM_NVRAM_CheckHeader() function. The entry guard checks the buffer length
  against sizeof(bh), where bh is a pointer, instead of sizeof(*bh), the actual
  struct size. This allows …
severity: medium
cvss: 6.1
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-125
vendor: Red Hat
product: swtpm
affected:
  - swtpm (all versions)
  - 'virt:rhel/swtpm (all versions)'
  - swtpm (all versions)
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-08-21T19:22:31.516001Z'
published: '2026-08-19'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T00:43:52.168Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-75900'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-75900'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2517910'
    label: RHBZ#2517910
tags:
  - cve.org
epss: 0.00111
epssPercentile: 0.01356
ingestedAt: '2026-11-06T01:43:15.134Z'
---

## Overview

An out-of-bounds read vulnerability was found in swtpm's SWTPM_NVRAM_CheckHeader() function. The entry guard checks the buffer length against sizeof(bh), where bh is a pointer, instead of sizeof(*bh), the actual struct size. This allows an undersized buffer to pass validation, causing a 2-byte heap overread on 64-bit systems (6 bytes on 32-bit) when accessing the totlen field. This may cause daemon termination on some platforms and leaks heap data to the log.

## Affected

- `swtpm (all versions)`
- `virt:rhel/swtpm (all versions)`
- `swtpm (all versions)`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

### Workarounds

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Fixed version: 0.10.2