Security readout for executives and security teams
Plain-English summary
Older Telegram apps could mishandle animated stickers in a way that corrupts stack memory on a victim device. The issue affects Android before 7.1.0 build 2090, iOS before 7.1, and macOS before 7.1. Sources do not show active exploitation.
Executive priority
Prioritize remediation where Telegram is used on executive, privileged, or sensitive-user devices. The issue is old, but the attack path is remote content parsing, so unmanaged legacy clients remain the main concern.
Technical view
CVE-2021-31321 is a stack-based overflow in gray_split_cubic within Telegram's custom rlottie fork. A malicious animated sticker may let a remote attacker overwrite stack memory out-of-bounds. Public metadata does not provide CVSS, CWE, CPE, or confirmed exploit-in-the-wild evidence.
Likely exposure
Exposure is mainly unmanaged or stale endpoints still running Telegram Android <7.1.0 (2090), Telegram iOS <7.1, or Telegram macOS <7.1. Organizations with BYOD messaging use may have limited visibility.
Exploitation context
The cited sources frame animated stickers as a remote attack surface. The CVE says a malicious sticker might trigger out-of-bounds stack overwrite. KEV is false, and the provided sources do not claim observed exploitation.
Researcher notes
The source bundle identifies the vulnerable function and library fork but lacks CVSS scoring, CWE mapping, CPEs, and official vendor advisory detail. Treat exploitability beyond the stated malicious-sticker vector as unproven from these sources.
Mitigation direction
- Upgrade Telegram Android to 7.1.0 build 2090 or later.
- Upgrade Telegram iOS and macOS to 7.1 or later.
- Use MDM controls to block vulnerable Telegram versions where possible.
- Check Telegram or vendor guidance for any additional hardening advice.
- Limit unmanaged messaging app use on high-risk corporate devices.
Validation and detection
- Inventory installed Telegram versions across managed Android, iOS, and macOS devices.
- Confirm no Android build is below 7.1.0 build 2090.
- Confirm iOS and macOS Telegram versions are not below 7.1.
- Review BYOD policy coverage for business use of Telegram.
- Document exceptions where app version visibility is unavailable.
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-2021-31321 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-gray_split_cubic-stack-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.