Security readout for executives and security teams
Plain-English summary
Older Telegram clients could be attacked through a malicious animated sticker. The issue is a heap buffer overflow in Telegram’s custom rlottie code, which could let a remote attacker corrupt memory on a victim device. The source bundle does not show active exploitation or a CVSS score.
Executive priority
Prioritize remediation where Telegram is allowed on corporate devices or used by sensitive staff. The risk is credible because it is remotely reachable, but urgency depends on whether outdated clients remain present.
Technical view
CVE-2021-31320 affects Telegram Android before 7.1.0 build 2090, Telegram iOS before 7.1, and Telegram macOS before 7.1. The vulnerable function is VGradientCache::generateGradientColorTable in Telegram’s custom fork of rlottie, reachable through animated sticker processing.
Likely exposure
Exposure is limited to users still running the affected Telegram Android, iOS, or macOS versions. Organizations with managed mobile or desktop fleets should treat old Telegram installations as the main risk area.
Exploitation context
The provided sources describe remote delivery via a malicious animated sticker. The bundle does not identify KEV listing, active exploitation, public exploit use, or confirmed real-world campaigns.
Researcher notes
The record lacks CVSS, CWE, and detailed affected CPE data. Analysis should stay scoped to the named Telegram platforms and versions. Do not assume impact beyond heap memory corruption from animated sticker parsing.
Mitigation direction
- Update Telegram Android to 7.1.0 build 2090 or later.
- Update Telegram iOS and macOS to 7.1 or later.
- Use MDM or endpoint controls to block outdated Telegram clients.
- Check Telegram or vendor guidance for platform-specific remediation details.
Validation and detection
- Inventory Telegram versions across managed Android, iOS, and macOS devices.
- Flag Android clients below 7.1.0 build 2090.
- Flag iOS and macOS clients below version 7.1.
- Confirm update compliance through MDM, app inventory, or endpoint telemetry.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2021-31320 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://www.shielder.it/blog/2021/02/hunting-for-bugs-in-telegrams-animated-stickers-remote-attack-surface/CVE reference · x_refsource_MISC
- https://www.shielder.it/advisories/telegram-rlottie-vgradientcache-generategradientcolortable-heap-buffer-overflow/CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.