# CVE-2026-75900: Swtpm: swtpm: out-of-bounds read in swtpm_nvram_checkheader due to sizeof(pointer) vs sizeof(struct) mismatch

CVE-2026-75900 is fixed in swtpm on 1 platform, first by DEBIAN-CVE-2026-75900, released August 29, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-75900
- Priority: Routine
- CVSS: 6.1 (Moderate)
- EPSS: 0.0011
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 19, 2026
- Weakness: Out-of-bounds Read
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-75900

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | swtpm Debian 14 | 0.10.2-1 | [DEBIAN-CVE-2026-75900](https://patchblox.com/security/data/fix/linux/debian-cve-2026-75900.md) | Aug 29, 2026 |
| Linux | swtpm opensuse-leap 16.0 | 0.10.2-160000.1.1 | [OPENSUSE-SU-2026:22048-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22048-1.md) | Oct 7, 2026 |
| Linux | swtpm sles 15.7 | 0.9.0-150700.3.3.1 | [SUSE-SU-2026:4366-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4366-1.md) | Sep 28, 2026 |
| Linux | swtpm sles 16.0 | 0.10.2-160000.1.1 | [SUSE-SU-2026:24156-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24156-1.md) | Oct 7, 2026 |

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Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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