CVE-2021-31320

Exp

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.

Published: 2021-05-18 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-31320 is rated High Exploit Risk (66.4/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.22%). 2 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-31320

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-31320

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.79% 1.22% +0.43%
2 2026-02-27 0.47% 0.79% +0.32%
3 2026-02-18 — 0.47% —

Full EPSS history (13 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-31320

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.1 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 5.2 [email protected]
5.8 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.6 4.9 [email protected]

Weakness enumeration for CVE-2021-31320

OS Trackers for CVE-2021-31320

vendor priority summary link
debian unimportant CVE-2021-31320 unimportant priority: Debian including 1 source packages (rlottie), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-31320
ubuntu medium CVE-2021-31320 medium priority: Ubuntu including 1 source packages (rlottie), 15 status rows across 15 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, trusty, upstream, xenial): ignored 7, not-affected 4, DNE 2, needs-triage 1, released 1. https://ubuntu.com/security/CVE-2021-31320

Affected software / configurations for CVE-2021-31320

Vendor Product Version Raw CPE
telegram telegram < 7.1.0 cpe:2.3:a:telegram:telegram:*:*:*:*:*:android:*:*
telegram telegram < 7.1.0 cpe:2.3:a:telegram:telegram:*:*:*:*:*:iphone_os:*:*
telegram telegram < 7.1.0 cpe:2.3:a:telegram:telegram:*:*:*:*:*:macos:*:*

References for CVE-2021-31320

cvelogic Threat Intelligence