Quick answers
- Is CVE-2026-120757 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-120757 being exploited in the wild.
- How severe is CVE-2026-120757?
- Informational severity, published 3 November 2026.
- Which products and versions are affected?
- HDF Group HDF5 through 2.2.0.
- Is there a fix for CVE-2026-120757?
- A patch was published on 2026-10-08. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-120757 attacked?
- It is attacked with local access, in a software library.
- Am I affected by CVE-2026-120757?
- Check whether you run HDF Group HDF5 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A heap buffer over-read in H5L__extern_traverse() fails to validate the size of external link user data before parsing strings within it using strlen(). The vulnerable code ignores the udata_size parameter and continues reading until a null byte is found, allowing reads past the allocated buffer boundary. The vulnerability is triggered when a malicious external link is traversed during file object access, potentially incorporating adjacent heap memory into filenames or object paths the library attempts to open.
Affected products
- HDF Group HDF5 through 2.2.0
Timeline
- 2026-11-03: disclosed
- 2026-10-08: patched