Samsung has begun shipping its October 2026 security update to the Galaxy S25 series, including the S25, S25+, S25 Ultra, S25 FE, and S25 Edge, as well as the Z Fold 7 and Z Flip 7. The update is part of Samsung’s monthly security maintenance release and contains fixes for critical vulnerabilities, with no new features included in the changelog.
The update, which was first reported for the entire Galaxy S25 line and the two foldable devices, is now live. Specific software version numbers for the update include S931USQUDDZJB for the Galaxy S25, S936USQUDDZJB for the S25+, S938USQUDDZJB for the S25 Ultra, S731USQUACZJC for the S25 FE, S937USQUADZJB for the S25 Edge, F766USQUDCZJB for the Z Flip 7, and F966USQUDCZJB for the Z Fold 7.
Security Fixes and Changelog
The October update combines fixes from Google and Samsung. Google contributed 45 patches, including 9 critical fixes for Android framework and system vulnerabilities. Samsung added its own fixes, including four high-rated issues related to its semiconductor chips and 27 Samsung Vulnerabilities and Exposures (SVE) items. The bulletin specifies 13 of the 27 SVE bugs, with six rated as high and seven as moderate. The update also addresses specific issues, such as two critical MediaTek modem bugs that could be exploited by connecting to a rogue cell tower and several high-rated vulnerabilities in media and image parsers.
Context for the Update
This October security release is the second such update for some devices this month, an exception to Samsung’s typical monthly update schedule. The previous October update, which began rolling out mid-October, also delivered 62 security patches, including 45 from Google and 17 from Samsung, with no new features.
Detailed Vulnerability Breakdown
Google’s portion of the patch list includes two critical MediaTek modem vulnerabilities, CVE-2026-20519 and CVE-2026-20520, which stem from an out-of-bounds write in the modem due to a missing bounds check. These flaws could be exploited by a phone connecting to a rogue cell tower with no user interaction required. Samsung’s own contributions cover a range of issues. For media handling, the update fixes three bugs in Samsung’s HEIF photo decoder: CVE-2026-21124 and CVE-2026-21125, both rated High, and CVE-2026-21126, rated Moderate. Additional media parser fixes address vulnerabilities in the Matroska video reader and FLAC audio decoder.
Excludes Exynos Chip Fixes from S25 Rollout
The update is rolling out in stages, starting in South Korea for the Galaxy S25 series and is expected to expand to other regions in the coming days or weeks. Samsung notes that the rollout may take time, and users are advised to be patient while the update is distributed to all devices in a given region. It is important to note that the four high-rated Samsung Semiconductor fixes are for the company’s own Exynos chips and do not apply to the S25, S25+, and S25 Ultra models, which use Qualcomm’s Snapdragon 8 Elite for Galaxy processor in all regions.
