CVE 2021-31320

Telegram Android <7.1.0 (2090), Telegram iOS <7.1, and Telegram macOS <7.1 are affected by a Heap Buffer Overflow in the VGradientCache::generateGradientColorTable function of their custom fork of the rlottie library. A remote attacker might be able to overwrite heap memory out-of-bounds on a victim device via a malicious animated sticker.

See the CVE page on Mitre.org for more details.