Samsung Galaxy Watch4 R860ZCU2JZB5
SM-R860 1 country Wear OS 6.0

Samsung Galaxy Watch4 R860ZCU2JZB5 Firmware

Samsung Galaxy Watch4 R860ZCU2JZB5 is an Wear OS 6.0 firmware for China (CHC). It is the same firmware configured per region and carrier (CSC). Find your country below, verify the file and download for free. Compared with the previous build R860TBU1JYL6: bootloader binary raised from 1 to 2, so after installing it there is no way back to older builds. A newer build for SM-R860 is available: R860TBS2JZG3.

8.9/10 (38)102 times
Wear OS 6.0
OS Version
2026-02-12
Build Date
2026-01-01
Security patch
1
Countries
1
CSC codes
2
Bootloader binary

Bootloader binary 2. Flashing firmware with a lower binary is usually blocked by Samsung anti-rollback.

All regional downloads

Pick your region (CSC) to download the matching firmware package.

Paste your current build number from Settings > About phone (About tablet) > Software information, or the output of *#1234#.
    MODEM/CP Version: R860ZCU2JZB5
    ModelRegionCSC VersionRelease dateSizeFile nameDownload
    SM-R860
    CHC China
    		R860ZMK2JZB5 2026-03-09 2.983 GiB
    SM-R860_23_20260212161621_y0333dowxm_fac.zip

    No matching downloads

    How to flash R860ZCU2JZB5

    • R860ZCU2JZB5 has bootloader binary 2. Your device must run binary 2 or lower: it is the 5th character from the end of your current build number.
    • CSC: Use CSC for a clean install, to change the region (CSC code), to downgrade or to repair a device that does not boot.
    • HOME_CSC: Use HOME_CSC to update the same model and region while keeping your data. Back up anyway: a failed update can still require a reset.
    • The Download Mode key combo depends on the model: see all combos.
    Full flashing guide
    Beware: Manually flashing firmwares may brick your device. Use it at your own risk and follow our tutorial steps.

    What's new in R860ZCU2JZB5

    • Stability and reliability
    Device behavior has been improved.

    These changes may vary depending on the model, country, or network operator of the customer environment.

    Security patch: January 2026

    SMR Jan-2026 fixes 32 vulnerabilities, 2 of them critical. Android Security Bulletin: 21, Samsung Semiconductor: 4, Samsung-specific issues (SVE): 7.

    Most severe Samsung fixes:

    • high Improper input validation in SecSettings prior to SMR Jan-2026 Release 1 allows local attacker to access file with system privilege. User interaction is required for triggering this vulnerability. (CVE-2026-20969)
    • high Use After Free in PROCA driver prior to SMR Jan-2026 Release 1 allows local attackers to potentially execute arbitrary code. (CVE-2026-20971)
    • high Out-of-bounds read in libimagecodec.quram.so prior to SMR Jan-2026 Release 1 allows remote attacker to access out-of-bounds memory. (CVE-2026-20973)

    All fixes and Galaxy models with this patch

    Device specifications

    • Launched withWear OS
    • Display diagonal3.05 cm (1.2")
    • Display technologyOLED
    • Display resolution396 x 396 pixels
    • Processor frequency1.8 MHz
    • RAM1500 MB
    • Flash memory16 GB
    • Battery capacity247 mAh
    • Weight25.9 g
    • Band materialSilicone
    • Band colourBlack

    Frequently Asked Questions

    R860ZCU2JZB5 is Wear OS 6.0 firmware for Samsung Galaxy Watch4, released for China (CHC). It includes the 2026-01-01 security patch. Samsung built it on 2026-02-12.

    SMR Jan-2026 fixes 32 vulnerabilities, 2 of them critical. Android Security Bulletin: 21, Samsung Semiconductor: 4, Samsung-specific issues (SVE): 7.

    No. A newer build for SM-R860 is available: R860TBS2JZG3. Install it instead of R860ZCU2JZB5 unless you need this exact version. The previous build was R860TBU1JYL6.

    Download the package for your region (CSC) and unzip it. In Odin, load each file into the slot with the same name: BL, AP, CP (if the package has one) and CSC, or HOME_CSC to keep your data. Odin checks the built-in checksum of every .tar.md5 file before flashing. The download is 2.983 GiB; keep about twice that free on the computer to unzip it. The Samsung Galaxy Watch4 must be on bootloader binary 2 or lower.

    This build uses bootloader binary 2. It can be flashed on a Samsung Galaxy Watch4 running binary 2 or lower; if the device already has a higher binary, Odin stops with "SW REV CHECK FAIL". 12 other builds of this model use the same binary, so you can switch between them in both directions.

    Other builds and changelog for Samsung Galaxy Watch4

    • Security
    The device is protected with improved security.

    These changes may vary depending on the model, country, or network operator of the customer environment.

    No changelog details available.

    • Security
    The device is protected with improved security.

    These changes may vary depending on the model, country, or network operator of the customer environment.

    No changelog details available.

    • Stability and reliability
    Device behavior has been improved.
    • Security
    The device is protected with improved security.

    These changes may vary depending on the model, country, or network operator of the customer environment.

    Show 10 older builds

    • Stability and reliability
    Device behavior has been improved.

    These changes may vary depending on the model, country, or network operator of the customer environment.

    No changelog details available.

    • Stability and reliability
    Device behavior has been improved.

    These changes may vary depending on the model, country, or network operator of the customer environment.

    • Stability and reliability
    Device behavior has been improved.
    • Security
    The device is protected with improved security.

    These changes may vary depending on the model, country, or network operator of the customer environment.

    One UI 8 Watch Upgrade
    Get things done

    Stay on top of important tasks with the Now bar
    Check the information you need right now and start essential features straight from your watch face. Ongoing tasks will appear in the Now bar at the bottom of your watch face so you can check key information quickly.

    Do more with double pinch
    Just pinch your thumb and index finger together twice to scroll through notifications, control music, take pictures, and more. You can also customize what happens wh...

    • Stability and reliability
    Device behavior has been improved.

    These changes may vary depending on the model, country, or network operator of the customer environment.

    Model firmware by region