Integer Underflow Leads to Out-of-Bounds Read via Truncated Chunk in HDF5 Szip 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
- Severity4.7/10CVSS 4.7
- No patch0/5No signal
What would change the score
- Would score about 60 if added to CISA KEV
- Would score about 55 if CISA's SSVC rates exploitation active
- Would score about 27 if advisories confirm default setups are exposed
CVE-2026-120755 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 4.7 (medium) and affects Szip 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- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean?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? →
- 5/100 · 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
The HDF5 library (through version 2.2.0 and its szip compression filter) is affected when reading szip-compressed datasets from a malformed or truncated file. Exploitation can cause an out-of-bounds memory read that crashes the reading application, resulting in denial of service.
Read the original description
HDF5 through 2.2.0 contains an out-of-bounds read vulnerability in H5Z__filter_szip() in src/H5Zszip.c. When decoding a szip-compressed chunk, the function subtracts the 4-byte uncompressed-length header from the chunk length without first verifying that the chunk is at least 4 bytes long. A truncated or corrupted chunk shorter than the header causes the length calculation to wrap around to a very large value, and the decompressor reads far past the end of the chunk buffer. An attacker who can get a user or application to read a dataset from a crafted HDF5 file can cause a denial of service. Only builds with szip support (libaec or the szip library) are affected.
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 Szip Filter
fixed in 2.3.0
Evidence 1
- Repository
Corrections
None so far.
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Questions about CVE-2026-120755
Is CVE-2026-120755 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-2026-120755?
Szip Filter: before 2.3.0.Source: cve.now feed data
How do I fix CVE-2026-120755?
Upgrade to a fixed version: 2.3.0.Source: cve.now feed data