CVE-2021-31317

Exp

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

Published: 2021-05-18 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-31317 is rated High Exploit Risk (61.3/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 1.29%). 2 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +1.12% over the last day, indicating growing attacker interest. 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-2021-31317

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-2021-31317

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 0.17% 1.29% +1.12%
2 2026-02-24 0.42% 0.17% -0.25%
3 2026-02-23 — 0.42% —

Full EPSS history (18 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-31317

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.5 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N 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:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 1.8 3.6 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/I:N/A:N 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:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2021-31317

OS Trackers for CVE-2021-31317

vendor priority summary link
debian not yet assigned CVE-2021-31317 not yet assigned 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-2021-31317
ubuntu medium CVE-2021-31317 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-2021-31317

Affected software / configurations for CVE-2021-31317

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-2021-31317

cvelogic Threat Intelligence