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Microsoft is making a key security change to Outlook: it will stop rendering inline SVG (Scalable Vector Graphics) images within emails. Instead, users will see blank spaces where those graphics would have appeared. This alteration is designed to reduce risks tied to phishing attacks that exploit SVG content.
According to a Microsoft 365 Message Center update, this change will apply to both Outlook for Web and the new Outlook for Windows. While inline display is disabled, SVG files sent as attachments will still be viewable from the attachment area.
Why Microsoft Made This Move
SVG has gained popularity among attackers because it's flexible and supports scripting, interactivity, or redirects all of which can be abused for phishing or cross-site scripting (XSS) attacks. By disabling inline SVG rendering, Microsoft aims to cut off a vector that hackers have increasingly used in malicious email campaigns.
Microsoft says the change affects fewer than 0.1% of images in Outlook, so most users likely won’t notice much difference in day-to-day email usage. It’s part of a broader strategy to remove or restrict features historically exploited in attacks. Past actions include blocking risky Office file types, limiting macro execution, and disabling unsafe add-ins. (Bleeping Computer)
What Users Should Know
Here’s how the change will affect Outlook users:
- Inline SVG images disappear: Instead of seeing the graphic embedded inline, users will see an empty space in its place.
- SVG attachments still work: If an SVG is sent as a file attached to the email (not inline), Outlook will continue to allow it to be viewed.
- No impact on other image formats: Common formats like PNG, JPEG, GIF, etc., are unaffected and will continue to render normally.
- Security gain: This measure reduces an entire class of phishing vectors, particularly ones that can embed malicious content in SVGs.
Broader Efforts to Harden Outlook & Office Security
This SVG restriction is the latest in a series of moves by Microsoft to tighten security in its productivity software suite. During 2025, Outlook began blocking file types like .library-ms and .search-ms, which had been previously exploited in attacks targeting governments and enterprises.
Microsoft has also taken steps to disable or limit potentially dangerous functionality across Office and Windows, such as:
- Blocking macros by default (including legacy Excel 4.0 macros)
- Disabling untrusted XLL add-ins and ActiveX controls
- Restricting VBScript usage within Office documents
Why This Matters for You
While most users won’t feel the difference, this change is a meaningful win in the ongoing fight against phishing. Attackers often rely on subtle tricks hidden scripts, disguised links, or embedded content to bypass filters and fool users. By cutting off one of those trick paths, Microsoft is making email a little safer.
Organizations should take note: this reinforces the need for layered email defenses, security awareness training, and restricting potentially exploitable content types. It also underscores how even seemingly small changes in rendering or file support can have outsized security benefits.
To dig deeper into how Microsoft is evolving its security posture across Office and Windows, see my post on recent Microsoft security enhancements and what they mean.