CVE-2021-31321

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.1% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2021-05-18 · updated 2026-06-17
Weakness: CWE-787

Description

Telegram Android <7.1.0 (2090), Telegram iOS <7.1, and Telegram macOS <7.1 are affected by a Stack Based Overflow in the gray_split_cubic function of their custom fork of the rlottie library. A remote attacker might be able to overwrite Telegram's stack memory out-of-bounds on a victim device via a malicious animated sticker.

Affected products

Telegram: before 7.1.0 — fixed in 7.1.0

How to fix

Upgrade to a fixed version: Telegram 7.1.0. Check the vendor advisory for mitigations.

References

https://www.shielder.it/advisories/telegram-rlottie-gray_split_cubic-stack-buffer-overflow/
https://www.shielder.it/blog/2021/02/hunting-for-bugs-in-telegrams-animated-stickers-remote-attack-surface/
https://www.shielder.it/advisories/telegram-rlottie-gray_split_cubic-stack-buffer-overflow/
https://www.shielder.it/blog/2021/02/hunting-for-bugs-in-telegrams-animated-stickers-remote-attack-surface/

Get alerted when CVE-2021-31321 or the next vulnerability affects your stack