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

References

• https://nvd.nist.gov/vuln/detail/CVE-2021-31318
• https://www.shielder.it/advisories/telegram-rlottie-lotcomplayeritem-lotcomplayeritem-type-confusion/
• https://www.shielder.it/blog/2021/02/hunting-for-bugs-in-telegrams-animated-stickers-remote-attack-surface/