CVE-2026-26199: Buffer underflow in `H5Iget_name `/`H5G_get_name` if size is zero
Vulnerability summary
CVE-2026-26199 is a medium (CVSS 6.5) Buffer Underwrite vulnerability in hdfgroup hdf5. EPSS estimates a 0.35% chance of exploitation in the next 30 days, higher than 28.8% of scored vulnerabilities. 1 public exploit is recorded.
Not severe (CVSS 5.9, network access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Timeline
- 20-07-2026PublishedVulnerability first disclosed.
- 20-07-2026Last modifiedVulnerability information updated.
Description
HDF5 is a high-performance library and a file format specification that implements the HDF5 data model. If `H5Iget_name` is invoked on a group id with `0` for the size parameter, it will underflow when trying to place a null terminator in the buffer. This can occur if `H5Iget_name` is invoked in a way where `size` can be forced to zero, and there is important data before the `name` buffer.
CVSS metrics
6 scores · 4 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated5.9MediumCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- NVDNIST5.9MediumCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- OSV · UbuntuEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
- OSV · DebianEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
EPSS trend
Probability
0.35%
Chance of exploitation in the next 30 days
Percentile
29%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.35% 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 causeAffected systems
Known conditions: network-reachable, no authentication, user interaction (CVSS vector). Other conditions: not stated in public data.
Debian1 product
- hdf5All versions (No fix recorded)
Hdfgroup1 product
- hdf5≤ 1.14.6 | < 2.1.0
Ubuntu1 product
- hdf5All versions (No fix recorded)
3 vendors · 3 products
