Delta DIAScreen CVEs Patch to v1.6.1 for Out-of-Bounds Write

Delta Electronics’ DIAScreen, a widely used HMI/visualization component of the DIAStudio engineering suite, contains a set of file‑parsing memory‑corruption bugs that can result in out‑of‑bounds writes and memory corruption when a user opens a specially crafted project file. The vendor and national incident responders have assigned four new CVEs (CVE‑2025‑59297, CVE‑2025‑59298, CVE‑2025‑59299 and CVE‑2025‑59300) and have published fixes; affected DIAScreen builds up through v1.6.0 and earlier should be upgraded immediately to remediate the issue. The advisory text provided with the disclosure identifies the problem as out‑of‑bounds write conditions triggered by malicious project files, calculates medium‑high severity scores (CVSS v3.1 ≈ 6.6 / CVSS v4 ≈ 6.8), and recommends that operators apply Delta’s update to DIAScreen v1.6.1 as the primary mitigation.

Background / Overview​

Delta Electronics’ DIAScreen is part of the company’s DIAStudio automation engineering suite and is deployed in industrial environments worldwide — notably in energy and critical‑manufacturing sectors. Memory‑corruption bugs in HMI and engineering software are routinely high‑value targets because engineering workstations often hold logic, credentials and build artifacts that can be used to move laterally into OT assets. Historically, DIAScreen has been the subject of multiple coordinated disclosures (stack overflows and file‑parsing bugs in earlier releases), making prompt vendor patching and workstation hygiene essential. Public trackers and incident responders have repeatedly called out DIAScreen in earlier advisories, underlining a pattern that deserves attention.
This specific set of findings centers on four related CVEs that share the same practical attack vector: a valid user opens a maliciously crafted DIAScreen project file (or other DIAScreen‑importable artifact), causing the software to write outside an allocated buffer. That memory corruption can cause crashes and, depending on circumstances, may be leveraged to achieve code execution in the context of the DIAScreen process. Vendor and third‑party records place these CVEs in the medium‑high category by current scoring conventions and describe the attack complexity as low but requiring user interaction (open a file).

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What the advisory says (concise, verifiable summary)​

• Affected product: Delta Electronics DIAScreen (DIAScreen: Version 1.6.0 and prior).
• Vulnerability type: Out‑of‑bounds write (CWE‑787) triggered by parsing a maliciously crafted project file.
• Assigned CVEs: CVE‑2025‑59297, CVE‑2025‑59298, CVE‑2025‑59299, CVE‑2025‑59300. Each CVE was assessed with a CVSS v3.1 base score of 6.6 (vector AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H) and a CVSS v4 base score of 6.8 (vector CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N).
• Impact statement: Opening a malicious file can cause memory corruption; the primary risk is crashes/denial‑of‑service and, in some exploitation chains, potential arbitrary code execution in the process context.
• Mitigation: Delta released DIAScreen v1.6.1 and recommends updating all affected installations. CISA also reiterates standard ICS defensive measures (minimize network exposure, user awareness to avoid malicious files, and perform risk/impact analysis before deploying mitigations).

These core facts are corroborated by public vulnerability trackers and the NVD/CNA records which reflect the vendor’s advisory metadata and the assigned CWE mapping for an out‑of‑bounds write. Independent advisories and vendor disclosure summaries echo the same technical vector and remediation guidance.

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Technical analysis — how the bug works and why it matters​

Memory‑corruption via crafted project files​

The disclosed root cause is a failure to validate bounds appropriately when parsing user‑supplied file contents. When DIAScreen ingests a project or related file, certain fields or binary blocks can be sized or indexed incorrectly by the parser; if the software writes data without checking the destination size, it may write past the intended buffer boundary (an out‑of‑bounds write). That corruption can:

• Overwrite adjacent memory structures (control data, function pointers, return addresses), or
• Produce unpredictable application behavior and crashes that can be escalated in multi‑step exploit chains.

Modern exploit mitigations (ASLR, DEP, stack canaries) raise the bar but do not eliminate the risk. In Windows engineering workstations that host DIAScreen, a successful exploitation path may still allow attackers to run payloads with the same privileges as the DIAScreen process.

Attack model and prerequisites​

• Attack vector: Local / user‑interaction — an attacker must convince or coerce a legitimate user (engineer, integrator, vendor) to open a malicious project file or import a crafted artifact. The product’s default deployment does not expose a remote file‑upload service, so remote unauthenticated exploitation is not the assumed model.
• Privileges required: None beyond the user’s ability to open files in DIAScreen.
• Typical exposure paths: Email attachments, compromised project archives from third‑party contractors, shared network folders, or USB thumb drives introduced into an engineering workstation. These are well‑known ICS attack corridors and are explicitly noted in numerous CISA advisories for similar file‑parsing flaws.

Likely consequences in OT environments​

• Denial of service or application instability on engineering or operator workstations, potentially delaying diagnostics or control actions.
• If an exploit chain succeeds, arbitrary code execution inside the DIAScreen process could enable credential theft, tampering with project files, or deployment of secondary tools to pivot into adjacent systems. Given DIAScreen’s role in configuring and visualizing control logic, that escalation path is operationally meaningful for energy and manufacturing sectors.

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Verification and cross‑checks​

Multiple independent sources validate core claims:

• NVD / CNA metadata for the CVEs shows the CVE descriptions, CWE mapping to out‑of‑bounds write, and vendor‑supplied CVSS vectors — confirming the technical classification those scores reflect. The NVD entry for CVE‑2025‑59299 (one of the four CVEs in the set) lists the vulnerability description and references the vendor advisory.
• Public vulnerability aggregators (CVE Details and Tenable feeds) mirror the vendor advisory information and list the Delta product advisory as the primary remediation reference. These aggregators also list the same CWE (CWE‑787) and the same vendor advisory link, confirming consistency across trackers.
• Historical CISA advisories and ZDI (Trend Micro’s Zero Day Initiative) disclosures show that DIAScreen has been repeatedly subject to file‑parsing memory‑corruption bugs before — a pattern that lends context to the present disclosures and confirms the practical attack vector remains a malicious file opened by a user. ZDI advisories also document prior bug classes and researchers engaged in coordinated disclosure.

Caveat and caution: direct access to the vendor PDF (Delta‑PCSA‑2025‑00018) may be restricted or require vendor login in some cases. The vendor document is referenced by NVD and aggregators; where a vendor advisory page requires authentication, independent tracking sites still reliably reproduce the vendor’s remediation guidance and CVE metadata. When vendor PDFs are inaccessible, rely on NVD/CNA and reputable trackers for authoritative CVE vectors and patch pointers, but corroborate with vendor downloads where possible before wide deployment.

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Practical mitigation checklist — prioritized, operational steps​

Apply these actions immediately in the indicated order. Use change control and test updates in staging before wide deployment.

• Patch (Highest priority)
• Download and install DIAScreen v1.6.1 (or whatever vendor patch supersedes it) on all engineering and operator workstations that run DIAScreen. Validate installer integrity (checksums or code signing) before deployment. Primary mitigation is vendor patching; do this first.
• Contain and harden
• Isolate engineering workstations from general‑purpose user networks and from direct internet exposure. Use network segmentation and host‑based firewall rules to restrict inbound traffic.
• Remove or restrict external media use (USB drives). If removable media must be used, implement strict scanning and quarantine processes.
• Reduce file‑based attack surface
• Restrict the types and sources of project files engineers can open. Establish an allowlist for trusted suppliers and verify file provenance (use code signing / checksums for shared project packages where feasible).
• Train staff to treat unsolicited project files and unexpected attachments as high‑risk.
• Detection & monitoring
• Enable application‑level auditing where available and collect logs from engineering workstations for anomalous file‑open operations, repeated DIAScreen crashes, and unexpected child process creation.
• Monitor network egress from workstations to detect suspicious callbacks following a successful compromise.
• Recovery planning
• Ensure backups of DIAScreen configuration and project files are isolated and verified. Test restore processes in a controlled environment before applying them in production.
• Vulnerability management
• Track the four CVEs and subscribe to Delta and CISA advisory feeds for follow‑on updates (mitigation nuances, further CVSS adjustments, or exploit observations). Maintain an asset inventory so the presence of DIAScreen on any host can be quickly identified.

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Operational guidance for Windows administrators​

• Treat engineering workstations as high‑value assets. These Windows hosts are often used with elevated privileges or contain credentials and firmware artifacts. Apply the principle of least privilege—run DIAScreen under a non‑administrative user where feasible and isolate accounts and network paths used to transfer project files.
• Use endpoint detection tools tuned for memory‑corruption symptoms (repeated process crashes, suspicious module loads) and enable controlled application whitelisting for engineering instruments.
• Coordinate patch deployment with maintenance windows. For production OT environments, establish rollback and verification procedures; do not rush updates into critical systems without testing, but treat this set of CVEs as high‑priority because of the low attack complexity and the potential for escalation via social engineering.

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Risk assessment — strengths and remaining risks​

Notable strengths of the vendor/response​

• Delta issued a remedial release (v1.6.1) and the disclosure was coordinated via standard vulnerability channels (CVE assignments). That demonstrates an operational disclosure pipeline and means customers have an official fix path.
• The public CVSS vectors and CWE mappings allow defenders to quickly incorporate the findings into existing risk scoring and prioritization processes (vulnerability scanners, patch management).

Residual and systemic risks​

• The attack vector remains social engineering‑friendly: attackers only need to get a malicious file into an engineer’s hands. Training and email hygiene remain imperfect controls. Prior DIAScreen advisories show repeated file‑parsing issues, indicating a recurring class of risk in the product family.
• Workstations that are poorly segmented or that share network resources with OT assets increase blast radius. Even with a vendor patch, ecosystems with slow patch cadence (third‑party contractors, long lifecycle OT) will remain exposed until every DIAScreen instance is updated.
• Public proof‑of‑concept code and exploit details sometimes appear after coordinated disclosure; if proof‑of‑concepts are published, exploitation likelihood rises dramatically. At the time of the vendor advisory and related public trackers, there were no confirmed in‑the‑wild exploit reports, but that state can change rapidly. Operators should assume interest from threat actors and act accordingly.

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Incident response and detection playbook (compact)​

• If a DIAScreen host crashes or behaves erratically after opening an untrusted file, isolate the host from networks immediately and collect memory and application logs.
• Preserve the malicious file (quarantine and capture a hash) and forward to the vendor or incident response team for analysis.
• Search for other hosts that may have received the same project file via shared drives, email, or vendor uploads; treat them as suspected compromises until proven clean.
• After applying the vendor patch, run file integrity checks on DIAScreen program files and validate system binaries against known good images.
• Notify downstream OT owners if the engineering workstation had write access to PLC or device programs — assume potential tampering until a validated review is complete.

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Final assessment and recommendation​

Delta Electronics DIAScreen’s newly disclosed out‑of‑bounds write vulnerabilities re‑emphasize an enduring ICS lesson: engineering tools that parse collaborative project files are attractive attack canvases because they routinely accept content from outside sources and are used on high‑value Windows workstations. The combination of low attack complexity and a user‑interaction vector makes rapid patching and tighter file handling policies the practical first line of defense.
Immediate actions:

• Prioritize deployment of DIAScreen v1.6.1 to all affected workstations; validate installer integrity and test in staging first.
• Harden engineering workstation networks, enforce strict file provenance checks, and increase staff awareness around opening project files from untrusted sources.
• Integrate these CVEs into vulnerability management dashboards and monitoring rules. Cross‑check the remediation status and remain alert for follow‑on advisories or exploit reports.

All claims in this article were cross‑checked against vendor advisory metadata and public tracking sources; where vendor advisories require restricted access, independent tracker metadata (NVD / CVE aggregators and ZDI disclosures) were used to verify CVE identifiers, CWE mappings and CVSS vectors. Any vendor‑specific text or download pages that are behind authentication should be consulted directly by administrators with a Delta account before deployment to confirm checksums, installer names and possible additional mitigation notes.
Conclusion: patch promptly, tighten file handling procedures, and treat engineering workstations running DIAScreen as high‑priority assets within the ICS/OT security program.

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Source: CISA Delta Electronics DIAScreen | CISA