One UI 8.5 March Patch Update Breaks Custom Font Support

Do you use custom fonts on your Samsung Galaxy phone? Well, there’s some bad news. The company has quietly removed support for third-party fonts, limiting users to only official or partner options. This change appears on One UI 8.5 devices running the March 2026 security patch.

Samsung quietly limits custom fonts on Galaxy phones

Samsung recently pushed the One UI 8.5 beta update (which packs the March 2026 security patch) to a bunch of Galaxy devices. While users are getting a taste of the latest software experience, it also comes with a key change that affects customization.

For years, Samsung users could install custom fonts using third-party apps like zFont 3. However, that flexibility now appears to be limited. After the latest update, several users have reported (via Piunikaweb) that they fail to apply third-party custom fonts on their Galaxy devices. Moreover, the existing fonts disappear when users switch to another option.

The reason behind this change appears to be a security fix. Samsung’s March 2026 security patch notes a vulnerability identified as CVE-2026-20989. “Improper verification of cryptographic signature in Font Settings prior to SMR Mar-2026 Release 1 allows physical attackers to use custom font. The patch adds proper verification,” the description reads.

Meanwhile, the zFont 3 team took to Reddit to confirm that their app currently does not support One UI 8.5 without root access. According to the developers, Samsung has officially patched the hole that allowed bypassing font restrictions. It is worth mentioning that the company appears to block unofficial third-party font packages, while officially purchased fonts remain unaffected.

In a post on the XDA community, a user said that One UI previously used the proprietary FlipFont system for font management. This allowed third-party apps like zFont 3 to offer custom fonts by packaging them as FlipFont APKs. Now, the system accepts only font APKs signed by Monotype (official font partner) or by Samsung’s own platform key pass.

As of now, Samsung has not detailed the limitation beyond its brief security bulletin note. We’ll let you know if more information surfaces on the web.