CVE-2026-120755: Integer Underflow Leads to Out-of-Bounds Read via Truncated Chunk in HDF5 Szip Filter
CVE-2026-120755 is a vulnerability in Integer Underflow Leads to Out-of-Bounds Read via Truncated Chunk in HDF5 Szip Filter, rated Moderate by Microsoft, with a CVSS 3.1 base score of 5.5 (Medium). An attacker can exploit it by an attacker with local access, without any privileges and only if a user takes an action. Microsoft has not reported exploitation in the wild. The EPSS model estimates a 0.14% probability of exploitation activity in the next 30 days, higher than 3% of all scored vulnerabilities. Microsoft released the fix on 5 November 2026, outside Patch Tuesday. It affects 1 product in 1 product family (Open Source Software).
Key facts
- CVE ID
- CVE-2026-120755
- Severity
- Medium CVSS 5.5
- Microsoft severity
- Moderate
- Exploited in the wild
- No
- Publicly disclosed
- No
- EPSS
- 0.14% (percentile 3%)
- CISA KEV
- Not listed
- Released
- Last updated
- Patch Tuesday
- November 2026 Patch Tuesday
- Product families
- Open Source Software
CVSS score and vector
Microsoft scores CVE-2026-120755 at 5.5 (temporal 5.5) using CVSS 3.1. Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
| Metric | Value |
|---|---|
| Attack vector | Local |
| Attack complexity | Low |
| Privileges required | None |
| User interaction | Required |
| Scope | Unchanged |
| Confidentiality impact | None |
| Integrity impact | None |
| Availability impact | High |
Affected products (1)
Open Source Software
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| azl3 hdf5 1.14.6-6 on Azure Linux 3.0 | Release Notes | Security Update |
Revision history
| Version | Date | Description |
|---|---|---|
| 1.0 | Information published. |