Realme has started rolling out November 2021 security patch to Realme C12 devices in the month of November 2021, carrying a build number of C.09 and basic stability improvements. This update also brings the previous month security fixes and vulnerabilities.
Realme C12 was released on August, 2020 with Android 10 out-of the box.
This update comes with minor changes and an integrated November 2021 Security patch. Realme C12 got android 11 with Realme UI 2.0 update in July 2021. Related: Realme C15: November 2021 Security Patch with C.09 Build

Source>>Realme Community
| Android OS | Update | Release Date/Status | Estimated Months |
| Android 10 | Out-of-the-box | August 2020 | Nil |
| Android 11 | First OS update | July 2021 | 9 months |
| Android 12 | Second/Last OS update | Eligible | Unconfirmed |
The Realme C12 was released with an Android 10 in August 2020. Therefore, Android 11 is its first major OS update.
Hence, it is eligible for the upcoming Android 12 update and it will be its second/last major OS update. However, it is still unconfirmed.
Check out >>> Android 12 update list for Realme devices
The Realme C12 Android 11 Update with stable Realme UI 2.0 has been released with the November 2021 security patch carrying C.09 Build.
Once the update is available on your device, you can head over to Settings >> About Phone >> Software Update section to update your Realme device with the latest update.
Once again, this is a phased rollout and will be available to all the users very soon. Kindly be patient and wait for the update on your device.
The manual update link will be available on the website → https://www.realme.com/in/support/software-update
For more android updates please download our android app – available on the Play Store