Security readout for executives and security teams
Plain-English summary
CVE-2021-21862 is a high-severity flaw in GPAC’s MPEG-4 decoding. A malicious video file can trigger memory corruption when opened or processed. Business risk is highest where GPAC handles externally supplied media, such as upload pipelines, automated transcoding, or user-facing media tools.
Executive priority
Treat as high priority for any environment processing external video. If GPAC is only used in controlled internal workflows, prioritize inventory first, then remediate through normal vulnerability management.
Technical view
The issue is an integer truncation in GPAC Project Advanced Content v1.0.1 MPEG-4 parsing, specifically handling the “Xtra” FOURCC code. The truncation can cause improper memory allocation and a heap-based buffer overflow, creating potential confidentiality, integrity, and availability impact.
Likely exposure
Exposure is likely limited to systems, applications, or services using the affected GPAC version or commit to decode MPEG-4 content, especially untrusted videos. General web servers are not exposed unless GPAC is in their media-processing path.
Exploitation context
The CVE describes exploitation through a specially crafted MPEG-4 input and user interaction: convincing someone or some workflow to open the video. The provided sources do not state active exploitation, and this CVE is not marked KEV.
Researcher notes
Evidence supports a memory-safety bug in the MPEG-4 “Xtra” parser with CVSS 8.8. The bundle does not provide a fixed version, patch commit, proof of active exploitation, or CPE mapping, so validation should start with dependency discovery.
Mitigation direction
- Inventory GPAC and libgpac use across applications, containers, and media pipelines.
- Check GPAC vendor guidance for fixed versions or supported remediation.
- Avoid processing untrusted MPEG-4 files with affected GPAC builds.
- Isolate media parsing services with least privilege and containment controls.
- Disable GPAC-based MPEG-4 handling where it is not required.
Validation and detection
- Confirm whether GPAC v1.0.1 or the cited commit is present.
- Map every workflow that opens, previews, transcodes, or validates MPEG-4 files.
- Verify upload and ingestion services reject or sandbox untrusted media.
- Review crash telemetry for GPAC-related memory corruption or parser failures.
- Confirm remediation against vendor release notes or package metadata.
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.
CWE-680: Exact CWE lookup
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Open ATT&CK lookupCVE-2021-21862 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
- High
- CVSS
- 8.8 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
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 vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H2.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
8.8HighVector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://talosintelligence.com/vulnerability_reports/TALOS-2021-1298CVE 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.