CVE-2026-34734: HDF5: H5T__conv_struct Use After Free
Vulnerability summary
CVE-2026-34734 is a high (CVSS 7.8) Use After Free vulnerability in hdfgroup hdf5. EPSS estimates a 0.19% chance of exploitation in the next 30 days, higher than 9% of scored vulnerabilities. 1 public exploit is recorded.
Public exploit (GitHub, Date unknown)
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 1Timeline
- 09-04-2026PublishedVulnerability first disclosed.
- 15-07-2026Last modifiedVulnerability information updated.
Description
HDF5 is software for managing data. In 1.14.1-2 and earlier, a heap-use-after-free was found in the h5dump helper utility. An attacker who can supply a malicious h5 file can trigger a heap use-after-free. The freed object is referenced in a memmove call from H5T__conv_struct. The original object was allocated by H5D__typeinfo_init_phase3 and freed by H5D__typeinfo_term.
CVSS metrics
4 scores · 4 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated7.8HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated7.8HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- NVDNIST7.8HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS trend
Probability
0.19%
Chance of exploitation in the next 30 days
Percentile
9%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.19% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
1 foundHdf5
Maturity: poc
Weaknesses
CWE · root cause- CWE-416Use After FreeThe product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
- CWE-825Expired Pointer DereferenceThe product dereferences a pointer that contains a location for memory that was previously valid, but is no longer valid.
Affected systems
Known conditions: local access, no authentication, user interaction (CVSS vector). Other conditions: not stated in public data.
Debian1 product
- hdf5All versions (No fix recorded)
Hdfgroup1 product
- hdf5≤ 1.14.1-2 | < 1.14.1-2
Ubuntu1 product
- hdf5All versions (No fix recorded)
3 vendors · 3 products
References
7 links- github.com/HDFGroup/hdf5/security/advisories/GHSA-w7v2-9cmr-pwwjX Refsource CONFIRMREPORTExploitVendor Advisory
