CVE-2026-120756
Heap Buffer Over-read via Malformed Message Size in HDF5's H5O__chunk_deserialize
HDF5 through 2.2.0 contains a heap buffer over-read vulnerability in H5O__chunk_deserialize() in src/H5Ocache.c. When decoding object header messages, the declared message size is checked against the end of the chunk image before the remainder of the message header (flags, and for version 2 object headers, the optional creation index) has been decoded. Because the message body begins after these fields, a message can start up to four bytes further into the chunk than the size check accounts for. A crafted HDF5 file can declare a message size that passes the check but extends past the end of the chunk image, causing the message’s decode callback, for example H5O__mtime_new_decode() in src/H5Omtime.c, to read beyond the heap allocation. The flaw is reachable during H5Fopen() on a crafted file. An attacker who can get a user or application to open a malicious file can cause a denial of service or limited disclosure of process memory.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Passive
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
1.9
Heap Buffer Over-read via Malformed Message Size in HDF5's H5O__chunk_deserialize
HDF5 through 2.2.0 contains a heap buffer over-read vulnerability in H5O__chunk_deserialize() in src/H5Ocache.c. When decoding object header messages, the declared message size is checked against the end of the chunk image before the remainder of the message header (flags, and for version 2 object headers, the optional creation index) has been decoded. Because the message body begins after these fields, a message can start up to four bytes further into the chunk than the size check accounts for. A crafted HDF5 file can declare a message size that passes the check but extends past the end of the chunk image, causing the message’s decode callback, for example H5O__mtime_new_decode() in src/H5Omtime.c, to read beyond the heap allocation. The flaw is reachable during H5Fopen() on a crafted file. An attacker who can get a user or application to open a malicious file can cause a denial of service or limited disclosure of process memory.
- Record
CVE-2026-120756- CVSS 4.0
- 1.9 Low
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:P - Weakness
- CWE-125
- Updated
- 2026-11-03
EUVDEUVD-2026-116008
1.9
HDF5 through 2.2.0 contains a heap buffer over-read vulnerability in H5O__chunk_deserialize() in src/H5Ocache.c. When decoding object header messages, the declared message size is checked against the end of the chunk image before the remainder of the message header (flags, and for version 2 object headers, the optional creation index) has been decoded. Because the message body begins after these fields, a message can start up to four bytes further into the chunk than the size check accounts for. A crafted HDF5 file can declare a message size that passes the check but extends past the end of the chunk image, causing the message’s decode callback, for example H5O__mtime_new_decode() in src/H5Omtime.c, to read beyond the heap allocation. The flaw is reachable during H5Fopen() on a crafted file. An attacker who can get a user or application to open a malicious file can cause a denial of service or limited disclosure of process memory.
- Record
EUVD-2026-116008- CVSS 4.0
- 1.9 Low
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:P - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-m9xj-6f2h-rx5r
1.9
HDF5 through 2.2.0 contains a heap buffer over-read vulnerability in H5O__chunk_deserialize() in...
HDF5 through 2.2.0 contains a heap buffer over-read vulnerability in H5O__chunk_deserialize() in src/H5Ocache.c. When decoding object header messages, the declared message size is checked against the end of the chunk image before the remainder of the message header (flags, and for version 2 object headers, the optional creation index) has been decoded. Because the message body begins after these fields, a message can start up to four bytes further into the chunk than the size check accounts for. A crafted HDF5 file can declare a message size that passes the check but extends past the end of the chunk image, causing the message’s decode callback, for example H5O__mtime_new_decode() in src/H5Omtime.c, to read beyond the heap allocation. The flaw is reachable during H5Fopen() on a crafted file. An attacker who can get a user or application to open a malicious file can cause a denial of service or limited disclosure of process memory.
- Record
GHSA-m9xj-6f2h-rx5r- CVSS 4.0
- 1.9 Low
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/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 - CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H - Weakness
- CWE-125
- Updated
- 2026-11-03
NVD
1.9
HDF5 through 2.2.0 contains a heap buffer over-read vulnerability in H5O__chunk_deserialize() in src/H5Ocache.c. When decoding object header messages, the declared message size is checked against the end of the chunk image before the remainder of the message header (flags, and for version 2 object headers, the optional creation index) has been decoded. Because the message body begins after these fields, a message can start up to four bytes further into the chunk than the size check accounts for. A crafted HDF5 file can declare a message size that passes the check but extends past the end of the chunk image, causing the message’s decode callback, for example H5O__mtime_new_decode() in src/H5Omtime.c, to read beyond the heap allocation. The flaw is reachable during H5Fopen() on a crafted file. An attacker who can get a user or application to open a malicious file can cause a denial of service or limited disclosure of process memory.
- Record
CVE-2026-120756- CVSS 4.0
- 1.9 Low
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/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 - CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H - Weakness
- CWE-125
- Updated
- 2026-11-04
OSV
1.9
Heap Buffer Over-read via Malformed Message Size in HDF5's H5O__chunk_deserialize
HDF5 through 2.2.0 contains a heap buffer over-read vulnerability in H5O__chunk_deserialize() in src/H5Ocache.c. When decoding object header messages, the declared message size is checked against the end of the chunk image before the remainder of the message header (flags, and for version 2 object headers, the optional creation index) has been decoded. Because the message body begins after these fields, a message can start up to four bytes further into the chunk than the size check accounts for. A crafted HDF5 file can declare a message size that passes the check but extends past the end of the chunk image, causing the message’s decode callback, for example H5O__mtime_new_decode() in src/H5Omtime.c, to read beyond the heap allocation. The flaw is reachable during H5Fopen() on a crafted file. An attacker who can get a user or application to open a malicious file can cause a denial of service or limited disclosure of process memory.
- Record
CVE-2026-120756- CVSS 4.0
- 1.9 Low
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:P - Weakness
- CWE-125
- Updated
- 2026-11-05
OSVDEBIAN-CVE-2026-120756
6.1
HDF5 through 2.2.0 contains a heap buffer over-read vulnerability in H5O__chunk_deserialize() in src/H5Ocache.c. When decoding object header messages, the declared message size is checked against the end of the chunk image before the remainder of the message header (flags, and for version 2 object headers, the optional creation index) has been decoded. Because the message body begins after these fields, a message can start up to four bytes further into the chunk than the size check accounts for. A crafted HDF5 file can declare a message size that passes the check but extends past the end of the chunk image, causing the message’s decode callback, for example H5O__mtime_new_decode() in src/H5Omtime.c, to read beyond the heap allocation. The flaw is reachable during H5Fopen() on a crafted file. An attacker who can get a user or application to open a malicious file can cause a denial of service or limited disclosure of process memory.
- Record
DEBIAN-CVE-2026-120756- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H - Updated
- 2026-11-04
OSVUBUNTU-CVE-2026-120756
1.9
HDF5 through 2.2.0 contains a heap buffer over-read vulnerability in H5O__chunk_deserialize() in src/H5Ocache.c. When decoding object header messages, the declared message size is checked against the end of the chunk image before the remainder of the message header (flags, and for version 2 object headers, the optional creation index) has been decoded. Because the message body begins after these fields, a message can start up to four bytes further into the chunk than the size check accounts for. A crafted HDF5 file can declare a message size that passes the check but extends past the end of the chunk image, causing the message’s decode callback, for example H5O__mtime_new_decode() in src/H5Omtime.c, to read beyond the heap allocation. The flaw is reachable during H5Fopen() on a crafted file. An attacker who can get a user or application to open a malicious file can cause a denial of service or limited disclosure of process memory.
- Record
UBUNTU-CVE-2026-120756- CVSS 4.0
- 1.9 Low
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:P - CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H - Updated
- 2026-11-05
OSVAZL-112634 No score
CVE-2026-120756 affecting package hdf5 1.14.6-6
HDF5 through 2.2.0 contains a heap buffer over-read vulnerability in H5O__chunk_deserialize() in src/H5Ocache.c. When decoding object header messages, the declared message size is checked against the end of the chunk image before the remainder of the message header (flags, and for version 2 object headers, the optional creation index) has been decoded. Because the message body begins after these fields, a message can start up to four bytes further into the chunk than the size check accounts for. A crafted HDF5 file can declare a message size that passes the check but extends past the end of the chunk image, causing the message’s decode callback, for example H5O__mtime_new_decode() in src/H5Omtime.c, to read beyond the heap allocation. The flaw is reachable during H5Fopen() on a crafted file. An attacker who can get a user or application to open a malicious file can cause a denial of service or limited disclosure of process memory.
- Record
AZL-112634- Updated
- 2026-11-05
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
hdf5Azure Linux:3 |
through 1.14.6-6 | None known |
hdf5Debian:12 |
All versions, plus listed versions 1.10.10+repack-11.10.10+repack-21.10.10+repack-31.10.10+repack-3.11.10.10+repack-3.2 Show 45 moreShow less1.10.10+repack-3.2+ports1.10.10+repack-3.31.10.10+repack-41.10.10+repack-51.10.8+repack1-11.12.0+repack-1~exp11.12.0+repack-1~exp21.12.2+repack-1~exp11.14.3+repack-1~exp11.14.3+repack1-1~exp21.14.3+repack1-1~exp31.14.4.3+repack-1~exp11.14.4.3+repack-1~exp21.14.4.3+repack-1~exp31.14.5+repack-11.14.5+repack-1~exp11.14.5+repack-1~exp21.14.5+repack-1~exp31.14.5+repack-1~exp41.14.5+repack-1~exp51.14.5+repack-1~exp61.14.5+repack-21.14.5+repack-31.14.5+repack-3.11.14.5+repack-3~exp11.14.5+repack-3~exp21.14.5+repack-3~exp31.14.5+repack-3~exp41.14.5+repack-41.14.5+repack-4~exp11.14.5+repack-4~exp21.14.5+repack-5~exp21.14.5+repack-5~exp31.14.6+repack-11.14.6+repack-1~exp11.14.6+repack-1~exp101.14.6+repack-1~exp111.14.6+repack-1~exp121.14.6+repack-1~exp131.14.6+repack-1~exp141.14.6+repack-1~exp151.14.6+repack-1~exp161.14.6+repack-1~exp171.14.6+repack-1~exp181.14.6+repack-1~exp19 |
None known |
hdf5Debian:13 |
All versions, plus listed versions 1.14.5+repack-31.14.5+repack-3.11.14.5+repack-41.14.5+repack-4~exp11.14.5+repack-4~exp2 Show 42 moreShow less1.14.5+repack-5~exp21.14.5+repack-5~exp31.14.6+repack-11.14.6+repack-1~exp11.14.6+repack-1~exp101.14.6+repack-1~exp111.14.6+repack-1~exp121.14.6+repack-1~exp131.14.6+repack-1~exp141.14.6+repack-1~exp151.14.6+repack-1~exp161.14.6+repack-1~exp171.14.6+repack-1~exp181.14.6+repack-1~exp191.14.6+repack-1~exp21.14.6+repack-1~exp201.14.6+repack-1~exp211.14.6+repack-1~exp31.14.6+repack-1~exp41.14.6+repack-1~exp51.14.6+repack-1~exp61.14.6+repack-1~exp71.14.6+repack-1~exp81.14.6+repack-1~exp91.14.6+repack-21.14.6+repack-3~exp12.1.0+repack-12.1.0+repack-1~exp102.1.0+repack-1~exp112.1.0+repack-1~exp32.1.0+repack-1~exp42.1.0+repack-1~exp52.1.0+repack-1~exp62.1.0+repack-1~exp72.1.0+repack-1~exp82.1.0+repack-1~exp92.2.0+repack-12.2.0+repack-22.2.0+repack-32.2.0+repack-42.2.0+repack-52.2.0+repack-6 |
None known |
hdf5Debian:14 |
All versions, plus listed versions 1.14.5+repack-31.14.5+repack-3.11.14.5+repack-41.14.5+repack-4~exp11.14.5+repack-4~exp2 Show 42 moreShow less1.14.5+repack-5~exp21.14.5+repack-5~exp31.14.6+repack-11.14.6+repack-1~exp11.14.6+repack-1~exp101.14.6+repack-1~exp111.14.6+repack-1~exp121.14.6+repack-1~exp131.14.6+repack-1~exp141.14.6+repack-1~exp151.14.6+repack-1~exp161.14.6+repack-1~exp171.14.6+repack-1~exp181.14.6+repack-1~exp191.14.6+repack-1~exp21.14.6+repack-1~exp201.14.6+repack-1~exp211.14.6+repack-1~exp31.14.6+repack-1~exp41.14.6+repack-1~exp51.14.6+repack-1~exp61.14.6+repack-1~exp71.14.6+repack-1~exp81.14.6+repack-1~exp91.14.6+repack-21.14.6+repack-3~exp12.1.0+repack-12.1.0+repack-1~exp102.1.0+repack-1~exp112.1.0+repack-1~exp32.1.0+repack-1~exp42.1.0+repack-1~exp52.1.0+repack-1~exp62.1.0+repack-1~exp72.1.0+repack-1~exp82.1.0+repack-1~exp92.2.0+repack-12.2.0+repack-22.2.0+repack-32.2.0+repack-42.2.0+repack-52.2.0+repack-6 |
None known |
hdf5Ubuntu:Pro:14.04:LTS |
All versions, plus listed versions 1.8.11-3ubuntu11.8.11-5ubuntu11.8.11-5ubuntu21.8.11-5ubuntu61.8.11-5ubuntu71.8.11-5ubuntu7.11.8.11-5ubuntu7.1+esm11.8.11-5ubuntu7.1+esm2 |
None known |
hdf5Ubuntu:Pro:16.04:LTS |
All versions, plus listed versions 1.8.15-patch1+docs-41.8.15-patch1+docs-51.8.16+docs-11.8.16+docs-21.8.16+docs-3 Show 6 moreShow less1.8.16+docs-3ubuntu11.8.16+docs-41.8.16+docs-4ubuntu11.8.16+docs-4ubuntu1.11.8.16+docs-4ubuntu1.1+esm11.8.16+docs-4ubuntu1.1+esm2 |
None known |
hdf5Ubuntu:Pro:18.04:LTS |
All versions, plus listed versions 1.10.0-patch1+docs-41.10.0-patch1+docs-4ubuntu0.1~esm11.10.0-patch1+docs-4ubuntu0.1~esm2 |
None known |
hdf5Ubuntu:Pro:20.04:LTS |
All versions, plus listed versions 1.10.4+repack-101.10.4+repack-111.10.4+repack-11ubuntu11.10.4+repack-11ubuntu1+esm1 |
None known |
hdf5Ubuntu:22.04:LTS |
All versions, plus listed versions 1.10.6+repack-51.10.7+repack-4ubuntu11.10.7+repack-4ubuntu2 |
None known |
hdf5Ubuntu:24.04:LTS |
All versions, plus listed versions 1.10.8+repack1-1ubuntu11.10.10+repack-3ubuntu11.10.10+repack-3.1ubuntu31.10.10+repack-3.1ubuntu4 |
None known |
hdf5Ubuntu:26.10 |
All versions, plus listed versions 1.14.6+repack-22.2.0+repack-42.2.0+repack-5 |
None known |
hdf5Ubuntu:26.04:LTS |
All versions, plus listed versions 1.14.5+repack-3build11.14.5+repack-41.14.6+repack-2 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, aliases, references | OSV | |
| affected, aliases, references | OSV | |
| references | OSV | |
| references | GitHub Advisories, NVD | |
| published | EUVD | |
| published | EUVD, NVD | |
| aliases, references | CVE List, GitHub Advisories, NVD | |
| aliases, products, published | EUVD | |
| first indexed | CVE List |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-120756 is a low vulnerability (CVSS 1.9) in Hdfgroup Hdf5, published November 3, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.18%, the 7th percentile. No source names a fixed version.
References
github.com/HDFGroup/hdf5/pull/6589
github.com/HDFGroup/hdf5/issues/6401
nvd.nist.gov/vuln/detail/CVE-2026-120756
github.com/advisories/GHSA-m9xj-6f2h-rx5r
github.com/CVEProject/cvelistV5/tree/main/cves/2026/120xxx/CVE-2026-120756.json
security-tracker.debian.org/tracker/CVE-2026-120756
ubuntu.com/security/CVE-2026-120756
cve.org/CVERecord?id=CVE-2026-120756
github.com/HDFGroup/hdf5/commit/10f1af5528168c5a71a58eba0b486e0677f3aaa3
Left out here: 28 versions. The JSON record has them.