HDF5 1.14.6 contains a heap buffer overflow in the Scale‑Offset filter (H5Z__filter_scaleoffset) that can be triggered by malformed HDF5 files and has been assigned CVE‑2025‑44905, creating a realistic denial‑of‑service and memory‑corruption risk for any software or service that reads untrusted HDF5 data.
Background / Overview
HDF5 is a widely used binary container and library for scientific data, image stacks, sensor logs and other large, structured datasets. The library provides a set of filters that can be applied to dataset storage; one of them, the
Scale‑Offset filter, is intended to store numeric data more compactly by scaling and offsetting values during compression and decompression. A heap buffer overflow in the implementation of that filter was reported in HDF5 version
1.14.6 and tracked as
CVE‑2025‑44905. Multiple vulnerability databases and vendor trackers list CVE‑2025‑44905 and describe the root cause as a heap‑based overflow in the function
H5Z__filter_scaleoffset (the Scale‑Offset filter path). The NVD entry for the CVE states the overflow and references an external proof‑of‑concept repository.
What the vulnerability is — technical summary
The code path and root cause
- The vulnerability occurs in the Scale‑Offset filter implementation, in the H5Z__filter_scaleoffset code path inside the HDF5 C library.
- A malformed Scale‑Offset encoded block (for example, a crafted bit/byte sequence inside a dataset chunk using that filter) can cause the code to read or write beyond a heap allocation — a classic heap buffer overflow (CWE‑122).
- Public trackers and advisory notes describe the immediate technical effect as reading or writing one byte beyond a small heap allocation used by the filter, producing memory corruption and potential crashes.
Why this matters in practice
A heap buffer overflow inside a dataset decoding path is dangerous because:
- It can cause process crashes immediately (availability impact).
- It can corrupt heap metadata or adjacent objects, which under specific allocator and runtime conditions might be leveraged to escalate to remote code execution — though reliable exploitation for RCE typically requires additional conditions and there is no consensus that RCE is trivial in this case. Trackers emphasize availability and integrity consequences first; claims about RCE should be treated with caution until confirmed by multiple, trusted exploit writeups.
Affected versions and scope
- Confirmed affected: HDF5 v1.14.6 (the vulnerability record explicitly lists that release).
- Multiple other HDF5 CVEs were reported around the same release window across different internal functions; this CVE is one of several memory‑safety defects cataloged against the 1.14.6 release, so the overall attack surface for that single release is larger than one CVE. Distribution trackers and maintainers have enumerated a number of 1.14.6 issues requiring coordinated fixes.
- Exposure is limited to contexts that decode or process datasets that use the Scale‑Offset filter. Consumers that never decode Scale‑Offset compressed datasets, or are built without support for that filter, are not directly vulnerable — however, in practice many toolchains (scientific tools, file converters, thumbnailers, cloud ingestion pipelines) link the full library and may be exposed.
Impact: availability, integrity, and confidentiality
The Microsoft Security Research Center (MSRC) description you referenced emphasizes availability loss: exploitation leads to
total loss of availability for the impacted component (the vulnerable process or service), either sustained while the attack continues or persistent after the attack completes. That mapping reflects real world consequences: repeated crashes, resource exhaustion, or persistent corruption of service state can cause long outages. The public vulnerability records and vendor trackers corroborate that the dominant immediate impact is denial‑of‑service and application instability. Important impact points:
- Availability (most severe): repeated triggering of the overflow can crash processes, cause worker pool churn and produce persistent unavailability in server‑side ingestion, processing or visualization pipelines that automatically open untrusted HDF5 files.
- Integrity (possible): heap corruption can sometimes be escalated to data corruption or more serious integrity issues depending on where memory is corrupted. However, reports emphasize DoS and corruption rather than immediate, reliable code execution.
- Confidentiality (lower): an overflow that causes reads beyond buffer bounds may leak memory in some code paths, but the Scale‑Offset bug is primarily cataloged as an overflow (write/read beyond bounds) with availability consequences first.
Exploitability and PoC status
- Public trackers (NVD and several third‑party databases) reference a researcher PoC (a crash report repository) that demonstrates a reproducible crash against HDF5 1.14.6 when decoding crafted Scale‑Offset data. The NVD entry links to a GitHub crash_report repository used as a reproduction artifact. That indicates a working proof‑of‑concept exists that can reliably cause a crash.
- Exploitability for remote compromise depends entirely on the deployment context:
- If a server accepts untrusted HDF5 files (uploads, automated conversion, cloud ingestion, preview pipelines) and passes them to an unpatched HDF5 build, attackers can trigger the crash remotely by uploading a crafted file — turning a local decoding bug into a remotely‑triggerable Denial‑of‑Service vector.
- Desktop apps that only open local files require the attacker to convince a user to open the file (social engineering) — lower scope for mass remote exploitation but still significant in targeted attacks.
- Whether the PoC can be extended to reliable code execution is unverified in public advisories. Several trackers caution that while heap corruptions can be escalated to exploitation on some runtimes, turning a proof‑of‑concept crash into a dependable RCE payload depends on allocator behavior, process hardening (ASLR, hardened allocators), and other exploitation mitigations. Treat claims of RCE as speculative unless demonstrated by multiple independent researchers.
Vendor and distribution response — patching status and timelines
- At time of public reporting, distribution trackers (Debian/Ubuntu/SUSE) and multiple vulnerability databases marked HDF5 1.14.6 packages as vulnerable and tracked fixes across a series of PRs and commits; some of the fixes appeared as individual GitHub merges corresponding to specific functions and CVEs. However, the status of a single consolidated upstream patch release for all 1.14.6 CVEs varies between maintainers and distributions.
- Debian’s security tracker and upstream issue references show GitHub issue and PR numbers and point to commits intended to remediate specific overflow conditions. Some distributions postponed mass updates pending consolidated fixes; their trackers list packages as “vulnerable” or “unfixed” until a vendor‑released patched version or distribution backport is packaged.
- The HDF Group’s release page documents the 1.14.6 release (the release date and notes), but CVE‑specific messaging and a designated fixed release for these specific 1.14.6 CVEs should be confirmed on the HDF Group security advisories and the HDF5 GitHub repository’s security/issue pages before rollout. Administrators should not assume a single point release already contains every downstream backport — verify the specific fix commit or changelog entry in the vendor package you will deploy.
Cautionary note: different trackers have assigned different severity scores and priorities for related HDF5 CVEs. Some distribution trackers categorized a number of the 1.14.6 issues as “minor” for their package lifecycle, while independent vulnerability databases and enterprise scanners flagged some of the same flaws as high‑severity. This divergence is common: scoring and prioritization can differ between upstream, OS vendor and third‑party assessors. Confirm the exact package versions your environment ships and whether the vendor changelog explicitly references the CVE(s) before declaring a host remediated.
Practical remediation and mitigation playbook
Immediate actions (high priority)
- Inventory: locate every binary, package, container image and appliance that includes HDF5 1.14.6. Search hosts, CI artifacts and container registries for that specific library version. Prioritize internet‑facing ingestion endpoints and automated file processing workers.
- Patch: apply vendor or distribution updates that include the fix for CVE‑2025‑44905. If a vendor release explicitly lists the CVE or a commit hash that addresses the Scale‑Offset filter overflow, update and redeploy consumer processes and restart services. If your distribution has a backport package, apply the vendor‑supplied package and confirm the changelog contains the fix.
- Rebuild statically linked artifacts: for applications that statically link libhdf5 (common in some imaging tools or embedded builds), you must rebuild with the patched library and redeploy the resulting binaries. Replacing shared library packages alone is not sufficient when the library is statically compiled into products.
Short‑term mitigations (if immediate patching is not possible)
- Disable or restrict automated ingestion/preview of untrusted HDF5 files. Disable automated conversion, thumbnailing or previewing that would decode user‑supplied HDF5 datasets until the environment is patched.
- Implement sandboxing and process isolation: run HDF5 decoding in a constrained process with limited privileges, tight CPU/memory cgroups and resource limits so a crash or resource exhaustion cannot cascade to critical systems.
- Apply network controls: restrict which hosts or tenants can upload HDF5 files to ingestion endpoints; require authenticated and authorized uploads and scan uploaded files in quarantine before passing them to decode workers.
- Monitor for crashes: enable process‑level crash alerts (systemd/journalctl, container runtime logs, telemetry) and set high‑severity alerts for repeated worker restarts that may indicate exploitation attempts.
Developer guidance (for projects linking HDF5)
- If upstream fixes are available as patches, merge or vend the upstream commit and rebuild; add unit tests that exercise Scale‑Offset decode paths with edge cases to prevent regressions.
- Consider fault‑tolerant decoding wrappers: perform validation of filter headers and bounds before passing data into low‑level decode routines, and fail gracefully on suspicious or malformed datasets instead of attempting to decode them blindly.
- Add fuzz testing and continuous integration fuzzers that target H5Z filter implementations; memory‑safety bugs are repeatedly discovered by fuzzing and that coverage reduces recurrence risk.
Detection and indicators of compromise
- Frequent or reproducible crashes or SIGSEGVs in processes that parse HDF5 (h5dump, scientific toolchains, thumbnailers, server‑side converters) are a top indicator. Correlate crash timestamps with recent file uploads.
- Unusual worker restart churn, increased error rates for dataset reads, and OOM/killed tasks on processing nodes that decode HDF5 files are signals of exploitation attempts or malformed file attacks.
- Presence of publicly disclosed PoC files or crash reproduction files in incoming uploads (check file names and contents against known PoCs stored by research repos) is an immediate red flag.
Assessing real‑world risk for different environments
- Cloud file ingest services and public upload endpoints: high‑risk. These endpoints convert/upload/preview user‑provided HDF5 data at scale and can be triggered by unauthenticated attackers uploading a crafted HDF5 file that exercises the Scale‑Offset path. These services should be prioritized for patching and mitigation.
- Research workstations and desktop tools: moderate risk. Attack requires either a user to open a malicious file or for a service to auto‑process a file. Still consequential in targeted attacks within academia and engineering organizations where HDF5 is ubiquitous.
- Embedded appliances or vendor binaries (statistically linked libraries): high long‑tail risk. Devices that ship with prebuilt HDF5 1.14.6 and rarely get updates are likely to remain vulnerable if vendors do not issue firmware or software updates.
Why scoring varies and what defenders should assume
Different trackers assign different CVSS scores and priorities for HDF5 issues. For CVE‑2025‑44905:
- NVD’s entry noted the description but had not completed an enrichment or a canonical CVSS assessment at the time of publication.
- Third‑party risk engines (for example, Wiz) published a higher severity (CVSS v3.1 ≈ 8.8) emphasizing a high impact if the decode path is remotely reachable.
- Distribution security teams (Debian/Ubuntu) may assign different priorities based on the package versions they ship, their backporting policy, and the practical exposure on their platforms. Some distribution trackers marked the impact as lower or postponed updates pending an upstream consolidated fix.
Defenders should therefore:
- Assume high impact for internet‑facing ingestion services until proven otherwise.
- Use the vendor/distribution changelog to confirm whether an applied package contains the fix rather than relying on a generic CVSS value.
- Prioritize remediation by exposure: internet‑facing and automated processing services first, then internal tools and embedded builds.
Final analysis — strengths, weaknesses and residual risk
Strengths in the public response
- The vulnerability has been cataloged in mainstream trackers (NVD, CVE entries, distribution trackers) and PoCs are available, which speeds detection and testing for defenders.
- Multiple independent analyses and vendor trackers identify the specific function and trigger conditions, enabling targeted mitigations (disable Scale‑Offset decoding or isolate decoding processes).
Notable risks and weaknesses that remain
- Patch dispersion: fixes for the many HDF5 1.14.6 CVEs are being handled at the commit and PR level; distribution packaging and vendor backports may lag or vary across ecosystems. This causes a long‑tail risk for unpatched systems.
- PoC availability: publicly available PoCs that reproduce crashes increase the likelihood of opportunistic Denial‑of‑Service attacks against exposed ingestion endpoints.
- Uncertainty about escalation: while DoS is well supported by the available PoCs, reliable remote code execution remains unproven publicly for this specific CVE; defenders should protect for the worst‑case but not assume immediate, trivial RCE without evidence. Flag any claims of easy RCE as speculative until independently reproduced.
Clear, actionable checklist (rapid response)
- Inventory every service and binary that links to HDF5 v1.14.6 (shared and static).
- For exposed ingestion/preview services: stop automatic decoding of uploaded HDF5 files or move decoding to an isolated processing tier.
- Apply vendor/distribution patches that explicitly reference CVE‑2025‑44905 or the HDF Group commit that fixes the Scale‑Offset overflow. Verify changelogs.
- Rebuild all statically linked deliverables with the patched library.
- Monitor for crash indicators and suspicious uploads; quarantine suspect files for offline analysis.
Conclusion
CVE‑2025‑44905 is a confirmed heap buffer overflow in HDF5 v1.14.6's Scale‑Offset filter that reliably provokes crashes and carries a high operational risk for systems that decode untrusted HDF5 data. Public proof‑of‑concept material exists and several distributions and trackers list the issue; remediation requires targeted patching, rebuilds for statically linked artifacts, and short‑term controls (sandboxing, disabling auto‑decode) to blunt remote Denial‑of‑Service attacks. Defenders should treat internet‑facing HDF5 ingestion and automated decoding services as highest priority, verify vendor changelogs to confirm fixes, and follow the mitigation checklist until all affected artifacts are rebuilt with the patched library.
Source: MSRC
Security Update Guide - Microsoft Security Response Center