Description
HDF5 through 2.2.0 contains a heap buffer over-read vulnerability in H5L__extern_traverse() in src/H5Lexternal.c, the default traversal callback for external links. The callback locates the target file name and object path within the link’s user data using strlen() without validating the buffer against its stored size (udata_size, which was marked unused). A crafted HDF5 file containing an external link whose data is not NULL-terminated, or is too short to hold both strings, causes strlen() to read past the end of the udata heap buffer, and the derived object path pointer may also point outside the buffer. The overrun is unbounded and continues until a zero byte is found. The flaw is triggered when the malicious link is traversed, for example when opening an object through it. An attacker who can get a user or application to access a crafted file can cause a denial of service, and adjacent heap contents may be incorporated into the external file name or object path the library attempts to open.
Published: 2026-11-03
Score: 6.9 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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Remediation

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Tracking

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References
History

Tue, 03 Nov 2026 21:15:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:hdfgroup:hdf5:*:*:*:*:*:*:*:*
Metrics cvssV3_1

{'score': 7.1, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H'}


Tue, 03 Nov 2026 18:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 03 Nov 2026 17:00:00 +0000

Type Values Removed Values Added
First Time appeared Hdfgroup
Hdfgroup hdf5
Vendors & Products Hdfgroup
Hdfgroup hdf5

Tue, 03 Nov 2026 15:45:00 +0000

Type Values Removed Values Added
Description HDF5 through 2.2.0 contains a heap buffer over-read vulnerability in H5L__extern_traverse() in src/H5Lexternal.c, the default traversal callback for external links. The callback locates the target file name and object path within the link’s user data using strlen() without validating the buffer against its stored size (udata_size, which was marked unused). A crafted HDF5 file containing an external link whose data is not NULL-terminated, or is too short to hold both strings, causes strlen() to read past the end of the udata heap buffer, and the derived object path pointer may also point outside the buffer. The overrun is unbounded and continues until a zero byte is found. The flaw is triggered when the malicious link is traversed, for example when opening an object through it. An attacker who can get a user or application to access a crafted file can cause a denial of service, and adjacent heap contents may be incorporated into the external file name or object path the library attempts to open.
Title Heap Buffer Over-read via Non-Terminated Link Data in H5L__extern_traverse
Weaknesses CWE-125
References
Metrics cvssV4_0

{'score': 6.9, 'vector': 'CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: HDFG

Published:

Updated: 2026-11-03T17:52:58.130Z

Reserved: 2026-11-02T21:30:11.791Z

Link: CVE-2026-120757

cve-icon Vulnrichment

Updated: 2026-11-03T17:52:51.508Z

cve-icon NVD

Status : Analyzed

Published: 2026-11-03T16:17:23.090

Modified: 2026-11-03T21:09:06.000

Link: CVE-2026-120757

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-11-03T16:45:14Z

Weaknesses