CVE-2025-54907: Visio Heap Overflow - Patch and Mitigation Guide

Microsoft’s Security Response Center has published an advisory for CVE-2025-54907, describing a heap-based buffer overflow in Microsoft Office Visio that can allow an unauthorized attacker to execute code in the context of the user who opens a malicious file. This is a document‑parser memory‑corruption flaw that follows a long pattern of high‑impact Office vulnerabilities: a specially crafted Visio file can trigger unsafe heap handling in the Visio parsing stack, corrupt memory, and ultimately yield remote code execution under the local user’s privileges. The vendor advisory is listed in Microsoft’s Security Update Guide, but the page requires client‑side rendering and deeper product metadata (KB IDs, build lists, and formal CVSS vectors) were not directly retrievable from the raw MSRC page during verification.

Background​

Microsoft Visio — the diagramming and vector‑drawing component of the Office ecosystem — routinely processes files with complex, nested object graphs and legacy binary structures (.vsd, .vsdx and embedded OLE parts). That parsing complexity repeatedly exposes subtle memory‑safety defects such as heap overflows and use‑after‑free bugs. These classes of flaws are especially dangerous because the attacker’s input is a file the user is likely to open from email, cloud shares, or collaboration platforms — a vector that scales rapidly through phishing and supply‑chain distribution. Independent vendor and community analyses highlight that Office document parser bugs frequently reach CVSS 7.x–8.x ranges and are prioritized for immediate remediation when published.

What Microsoft’s advisory states (canonical points)​

• The MSRC entry exists for CVE‑2025‑54907 and lists Microsoft Office Visio as the affected component; the short public description identifies the class of flaw as a heap‑based buffer overflow enabling code execution with the current user’s privileges. Because the MSRC Security Update Guide is the vendor’s canonical source, administrators should treat the advisory as the authoritative statement. Note: the MSRC UI is dynamic and requires JavaScript to show the complete, per‑product table and KB mapping.
• At a high level the attack vector is file‑open: a maliciously crafted Visio document that, when opened (or possibly previewed) by a user, triggers the overflow condition. Historically, preview panes or thumbnail/preview handlers in Outlook and File Explorer have been attack vectors for similar vulnerabilities; this detail must be confirmed for CVE‑2025‑54907 by checking Microsoft’s full advisory metadata or the KB release notes.

Technical overview — heap‑based buffer overflow unpacked​

A heap‑based buffer overflow occurs when code allocates a buffer on the heap that is too small for the data copied into it, or when a length calculation for a copy is incorrect. In document parsers this often arises from:

• incorrectly parsed length fields in a file format,
• integer arithmetic errors (wrap/overflow) while computing allocations,
• missing bounds checks when copying embedded object data, or
• legacy format support that assumes older invariants.

When the overflow corrupts heap metadata or adjacent objects, an attacker can overwrite function pointers, vtable entries, or control‑data that will later be dereferenced, enabling arbitrary code to be executed or control flow to be redirected. Modern exploits combine the memory primitive with ROP chains, JIT‑spraying, or other techniques to bypass mitigations like DEP and ASLR. These mechanics are well documented across recent Office vulnerabilities and are consistent with Microsoft’s generic descriptions for Visio parser flaws.

Likely exploitation chain (high level)​

• Attacker crafts a Visio document with malformed internal length/record values.
• Victim receives the file (email attachment, cloud share, download) and opens or previews it in Visio.
• Visio’s parser allocates a heap buffer and performs an unchecked copy or miscomputed allocation, overflowing into adjacent memory.
• The overflowed data overwrites a pointer or control structure; subsequent dereference leads to attacker‑controlled execution context.
• Attacker executes payload with the same privileges as the Visio process (typically the user account). From there, common follow‑ons include credential theft, lateral movement, persistence mechanisms, and data exfiltration.

Who’s affected and how to verify impact​

• The advisory names Microsoft Office Visio as the affected product. Historically, Visio patches have been packaged for multiple Office channels: Microsoft 365 Apps (Click‑to‑Run), Office LTSC/perpetual releases (Office 2019, LTSC 2021/2024), and independent Visio installers. Organizations must verify affected builds and KB numbers using Microsoft Update channels (WSUS, SCCM/ConfigMgr, Microsoft Update Catalog) or the Security Update Guide API rather than relying solely on dynamic web UIs.
• Because MSRC’s web UI requires JavaScript to render full product matrices and KB identifiers, the best practice is to:
• query the Security Update Guide API for the CVE entry,
• check the Microsoft Update Catalog for matching KB articles,
• and confirm package availability via WSUS/SCCM inventory reports.

If an environment’s patching telemetry shows any Visio package/build that matches Microsoft’s affected list, those endpoints must be prioritized for remediation. The advisory’s existence in MSRC is the canonical confirmation that the flaw is real; secondary public databases may lag in indexing the CVE.

Verification and corroboration status​

• Canonical vendor listing: Microsoft’s Security Update Guide includes an entry for CVE‑2025‑54907. Because the MSRC page uses client‑side rendering, the advisor text is visible as the canonical record but the rendered details (CVSS score, per‑product CPEs, and KB IDs) may require the Security Update Guide API or user interaction to extract.
• Third‑party public trackers and vendor feeds: at the time of verification, many public trackers list a stream of Office/Visio memory‑safety CVEs across 2024–2025 with the same technical patterns (heap overflows and use‑after‑free) and similar severity ratings; however, explicit cross‑references for this exact CVE number (CVE‑2025‑54907) were not consistently present in every aggregator. That means some elements (exact CVSS vector, presence of in‑the‑wild exploitation, and KB package IDs) could not be confirmed outside of MSRC during the check. Where third‑party trackers have entries for related Visio CVEs, they consistently show local/document‑open attack vectors and high severity. Treat any uncorroborated numeric scores or exploit status as provisional until additional registries (NVD, MITRE CVE, or reputable vendors) publish matching metadata.
• Practical implication: rely on Microsoft’s advisory for remediation instructions and use your enterprise patching tools to confirm KB deployment. Cross‑check with reputable vendor advisories (EDR/AV vendor blogs, CISA) as they post correlated guidance.

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Immediate steps for system administrators (priority checklist)​

Apply the vendor patch as the primary remediation. If immediate patching is not possible, implement layered mitigations to reduce exposure until updates are deployed.

• Critical immediate actions
• Inventory Visio: enumerate every host with Microsoft Visio installed and capture product channel (Click‑to‑Run vs MSI) and build numbers.
• Patch deployment: obtain the KB/update package Microsoft publishes for CVE‑2025‑54907 and schedule rollout starting with high‑risk groups (admins, engineering workstations, systems that process external Visio files). Verify installation via your endpoint management tooling.
• Short‑term mitigations where patching must be staged
• Disable Visio file preview in File Explorer and the Outlook preview pane to avoid unintentional triggering via previews.
• Enforce Protected View for files originating from the Internet and block automatic enabling of macros or active content for Visio documents.
• Apply temporary application control policies (whitelisting) and restrict which users can launch Visio on sensitive hosts.
• Tighten email gateway rules and DLP policies to block or quarantine unsolicited .vsd/.vsdx attachments from external senders.
• Detection and response enhancements
• Add EDR rules to alert on Visio spawning uncommon child processes (PowerShell, cmd, wscript, cscript) and network exfil attempts immediately after a Visio process starts.
• Monitor for spikes of incoming Visio attachments from external sources and correlate with endpoint telemetry for suspicious activity.
• Create an IR playbook: isolate impacted hosts, capture volatile memory, and preserve Visio document artifacts for forensic analysis.

For SOC teams — telemetry to prioritize​

• High‑value signals:
• Visio.exe (or associated host processes) launching powershell.exe or cmd.exe unexpectedly.
• New processes writing to persistent locations immediately after Visio execution.
• Suspicious network connections originating right after a Visio file open.
• Correlation sources:
• Mail gateway logs (to identify the source and distribution of Visio attachments).
• EDR event chains and file reputation telemetry (to detect multiple recipients of the same suspicious file).
• Host filesystem events showing dropped artifacts in temp directories.

Tune detection rules to escalate incidents involving administrators or privileged accounts who open external Visio files: the impact of code execution under an admin context is far higher.

Operational risk and prioritization​

• Why this vulnerability matters: Office document RCEs are a favored attack technique for both targeted and commodity campaigns. A successful exploit can rapidly give attackers an initial foothold or be combined with privilege escalation to create a full enterprise compromise.
• Prioritization guidance for enterprises:
• Prioritize systems that frequently exchange Visio files across trust boundaries (engineering teams, contractors, shared collaboration servers).
• Treat the advisory as urgent: even if initial exploitation requires user interaction, the distribution mechanisms (phishing, cloud shares, public collaboration) mean that a local exploit can be scaled remotely by attackers.

Hardening recommendations beyond patching​

• Enforce principle of least privilege: prevent users from running daily sessions with administrative rights.
• Implement application control on high‑value endpoints (only allow known signed binaries to execute).
• Restrict network egress for endpoints that do not require external connectivity, minimizing data exfil options for an exploited process.
• Harden collaboration platforms: scan and block suspicious Visio uploads to SharePoint, Teams, and other file‑sharing services.

Detection recipes and sample EDR rules (operational)​

• Rule A: Alert when Visio.exe parent process is explorer.exe and child process is powershell.exe or cmd.exe; correlate with file hash unknown or low reputation.
• Rule B: Alert on creation of executable files or suspicious DLLs in user temp directories within 60 seconds of a Visio process start.
• Rule C: Detect unusually large volumes of outgoing traffic from a host within 5 minutes of a Visio file being opened.

Tune thresholds to reduce false positives in legitimate automation workflows; always correlate process spawning anomalies with file origin and user context.

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Threat modeling: likely adversary behaviors and timelines​

• Rapid weaponization: Historically, Office document parser vulnerabilities are quickly weaponized once proof‑of‑concepts appear. Attackers — both opportunistic criminals and advanced threat actors — focus on these bugs because they provide a straightforward initial access vector through socially engineered files. Expect to see phishing campaigns and targeted spear‑phishing attempts using plausible Visio attachments soon after public disclosure.
• Preview exploitation risk: If the vulnerability can be triggered by preview handlers (Outlook/File Explorer), the attack becomes even more potent because target users can be compromised without explicitly opening the file. Confirm whether preview handlers are impacted by checking Microsoft’s full advisory and the KB documentation. If previewing is in the attack surface, disabling previews should be treated as a top short‑term mitigation.

Strengths and limitations of publicly available information​

• Strengths
• Microsoft has listed CVE‑2025‑54907 in its Security Update Guide, which is the canonical vendor channel for vulnerability disclosures and mitigations. That ensures the advisories and patches will be distributed through standard Microsoft update mechanisms.
• Industry trackers and SOC guidance for similar Visio CVEs are mature: recommended mitigations (disable preview, enforce Protected View, patch promptly) are well understood and effective in risk reduction while patches are staged.
• Limitations and unverifiable aspects
• The MSRC entry requires JavaScript rendering for the full per‑product table and KB references; automated scraping may not return the KB identifiers or CVSS string. As a result, some specific metadata (official CVSS score, exact list of affected builds, and the KB article number that contains the fix) could not be independently extracted from the MSRC page during verification. Administrators should therefore use the Security Update Guide API or Microsoft Update Catalog to obtain canonical KB IDs and build mappings.
• At the time of verification, independent registries (NVD / MITRE / other trackers) may lag in their indexing for this specific CVE number. Absence of a mirrored entry in those systems does not invalidate Microsoft’s advisory; it merely means corroborating databases may be delayed. Treat any numeric severity or exploitation claims not published by Microsoft or validated registries as provisional.

Recommended rollout plan (practical, step‑by‑step)​

• Immediately inventory Visio installations and categorize by update channel and business criticality.
• Use Security Update Guide API / Microsoft Update Catalog to retrieve the KB for CVE‑2025‑54907, stage the update in a test cohort, and validate compatibility.
• Patch high‑risk hosts first (administrators, engineering design workstations, file servers that process Visio files).
• During rollout, implement short‑term mitigations (disable previews; enable Protected View for internet files; enforce application control).
• Post‑deployment: verify patch installation through endpoint telemetry, and increase SOC sensitivity for Visio‑triggered alerts for at least two weeks after rollout completion.
• Update IR playbooks and coordinate mail‑gateway rules to block mail containing Visio attachments from untrusted senders.

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Conclusion​

CVE‑2025‑54907 is a serious memory‑corruption vulnerability in Microsoft Office Visio described by Microsoft as a heap‑based buffer overflow that permits code execution when a malicious document is processed. The vendor’s Security Update Guide entry is the authoritative source for remediation; because the MSRC UI requires client‑side rendering, administrators should extract KB/package details via the Security Update Guide API or the Microsoft Update Catalog and deploy the vendor patch without delay. While third‑party trackers and historical patterns confirm the high potential impact of Visio parser flaws, some CVE metadata (CVSS numeric score, KB ID, and in‑the‑wild exploitation reports) were not consistently available across all public feeds at the time of verification — those elements should be confirmed directly from Microsoft’s update channels during patch planning. Until patches are applied, implement defensive measures (disable previews, enforce Protected View, tighten mail controls, and tune EDR rules) to substantially reduce the window of exposure.

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Source: MSRC Security Update Guide - Microsoft Security Response Center