Uninitialized Heap Memory Disclosure via Truncated Chunk in HDF5 Scale-Offset Filter
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 2.3.0
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 2.3.0.
- Exploitation0/40No signal
- Exposure?/25Exposure: unknown (data gap). No advisory context yet
- Reach?/20Reach: unknown (data gap). No tracked technology or package matched
- Severity1.9/10CVSS 1.9
- No patch0/5No signal
What would change the score
- Would score about 57 if added to CISA KEV
- Would score about 52 if CISA's SSVC rates exploitation active
- Would score about 24 if advisories confirm default setups are exposed
CVE-2026-120754 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 1.9 (low) and affects Scale-Offset Filter; fixed in 2.3.0.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 2/100 · provisional
- Fix
- Fixed in 2.3.0
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: partial
Summary
HDF5 (through version 2.2.0 as noted, but without version numbers here) is affected: its Scale-Offset filter can read uninitialized heap memory when decoding a truncated chunk in a crafted file. An attacker who gets a user or application to read a dataset from that file could leak unrelated process memory into the returned data.
Read the original description
HDF5 through 2.2.0 contains an uninitialized memory read vulnerability in H5Z__filter_scaleoffset() in src/H5Zscaleoffset.c. The decode path validates reads against the allocated size of the chunk buffer rather than the number of bytes actually read from the file. Because H5D__chunk_lock() deliberately sizes filtered chunk buffers to the larger of the stored and unfiltered chunk sizes and fills only the stored bytes, a truncated chunk passes these bounds checks and is decompressed from the uninitialized remainder of the allocation. Unrelated heap contents are then returned to the caller as dataset data. Because the reads remain within the allocation, the issue is not detected by AddressSanitizer. An attacker who can get a user or application to read a dataset from a crafted HDF5 file can cause disclosure of process memory. This issue exists because of an incomplete fix for CVE-2026-19029.
What to do
Upgrade to a fixed version: 2.3.0.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: partial
- Record last updated
Affected versions
- The HDF Group Scale-Offset Filter
fixed in 2.3.0
Evidence 1
- Repository
Corrections
None so far.
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Questions about CVE-2026-120754
Is CVE-2026-120754 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-120754?
Scale-Offset Filter: before 2.3.0.Source: cve.now feed data
How do I fix CVE-2026-120754?
Upgrade to a fixed version: 2.3.0.Source: cve.now feed data