CVSS 4.0
5.4 mediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:PCVE-2026-120758
Medium (5.4) in hdfgroup hdf5. EPSS 0.1% estimated probability of exploitation activity in the next 30 days.
On this page
HDF5 through 2.2.0 contains a NULL pointer dereference vulnerability in H5HL_unprotect() in src/H5HL.c. H5HL_protect() pins a single metadata cache entry for a local heap, either the heap prefix or the separate data block, and H5HL_unprotect() unpins it on the final unprotect. When the metadata cache destroys a corrupted local heap entry, H5HL__prfx_dest() unlinks it from the heap by setting heap->prfx or heap->dblk to NULL. A crafted HDF5 file can therefore reach H5HL_unprotect() with no cached object to unpin, and the function passes the NULL pointer to H5AC_unpin_entry(). This causes an assertion failure in debug builds and a NULL pointer dereference and crash in release builds. An attacker who can get a user or application to open and traverse a malicious file can cause a denial of service.
Severity
CVSS 3.1
5.5 mediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H- EPSS
- 0.1% estimated probability of exploitation activity in the next 30 days; 3rd percentile. Scored 2026-11-04. A forecast for this CVE across the internet, not for your own systems.
- CISA's assessment (SSVC)
- Exploitation: none · Automatable: no · Technical impact: partial, assessed 2026-11-03. From CISA's Vulnrichment in the CVE List: whether it is exploited, whether exploiting it can be automated, and how much control it gives.
- CWE
- CWE-476 NULL Pointer Dereference
- OWASP Top 10
- A10:2025 Mishandling of Exceptional Conditions
- Published
- Modified
- Record from
- the NVD, synced
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Affected
Versions
From the NVD's CPE matches.
| Product | Affected |
|---|---|
| hdfgroup:hdf5 | through 2.2.0 |
Linux distributions
| Distribution | Release | Package | Fixed in | Advisory |
|---|---|---|---|---|
| Debian | 12, 13, 14 | hdf5 | no fix listed | DEBIAN-CVE-2026-120758 |
| Azure Linux | 3 | hdf5 | no fix listed | AZL-112640 |
From the distributions' data via OSV.dev: the Debian Security Tracker; Microsoft's Azure Linux vulnerability data, MIT. Modified: reformatted and linked to CVE records. Credits. On the distributions' own pages: Debian.
Red Hat
Red Hat rates this Moderate.
A NULL pointer dereference vulnerability was found in HDF5's H5HL_unprotect() function in src/H5HL.c. When processing a crafted file containing corrupted local heap metadata, a previously destroyed cache entry leaves internal heap pointers unlinked, causing the library to pass a NULL pointer to H5AC_unpin_entry(). An attacker who convinces a user or application to open and traverse a specially crafted HDF5 file can trigger an application crash, resulting in a denial of service.
Restrict file permissions to ensure HDF5 files are ingested exclusively from verified, trusted sources. Run file-parsing workloads within isolated containers or constrained sandbox environments to limit the impact of process termination.
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux AI (RHEL AI) 3 | hdf5 | Fix deferred | |
| Red Hat Hardened Images | hdf5 | Affected | |
| Red Hat OpenStack Platform 13 (Queens) | hdf5 | Fix deferred |
Contains Red Hat Security Data © Red Hat, Inc., licensed under CC BY 4.0. Source: https://access.redhat.com/security/data. Modified: reformatted. Red Hat's page for CVE-2026-120758.