Security readout for executives and security teams
Plain-English summary
GPAC’s MPEG-4 decoder can mishandle a specially crafted video file. If a user or service processes that file, memory corruption may result, with potential confidentiality, integrity, and availability impact. The supplied sources rate this high severity, but do not show known active exploitation.
Executive priority
Treat as a high-priority exposure if GPAC handles customer, partner, or internet-sourced video. Urgency is lower where GPAC is absent or only processes trusted files. Confirm usage first, then remediate or isolate affected workflows.
Technical view
CVE-2021-21851 is an integer overflow in GPAC Project Advanced Content v1.0.1 MPEG-4 decoding, involving csgp decoder sample group description indices. Unchecked arithmetic can lead to a heap-based buffer overflow and memory corruption when crafted MPEG-4 input is opened.
Likely exposure
Exposure is most likely in systems, applications, or workflows using GPAC v1.0.1 or the listed commit to parse untrusted MPEG-4 files. No CPEs are supplied, so asset discovery may require package, source, and dependency review.
Exploitation context
The described attack requires convincing a user, application, or automated media workflow to open a crafted video. KEV is false in the supplied bundle, and no cited source here establishes active exploitation.
Researcher notes
The weakness is CWE-680: integer overflow leading to buffer overflow. CVSS 8.8 reflects network-deliverable input, low complexity, no privileges, required user interaction, and high impact. Supplied evidence does not identify a specific fixed release.
Mitigation direction
- Inventory GPAC deployments and embedded GPAC libraries.
- Prioritize systems that process untrusted MPEG-4 files.
- Check GPAC and Talos guidance for fixed versions or vendor advisories.
- Restrict untrusted media processing until remediation is confirmed.
- Run media parsing in sandboxed, least-privilege environments where possible.
Validation and detection
- Confirm whether GPAC v1.0.1 or the listed commit is present.
- Map services and desktop workflows that parse MPEG-4 files.
- Review dependency manifests, containers, and source builds for GPAC usage.
- Verify compensating controls around untrusted media ingestion.
- Document patch status and unresolved vendor guidance gaps.
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
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-21851 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-2021-1297CVE reference · x_refsource_MISC
- https://www.talosintelligence.com/vulnerability_reports/TALOS-2021-1297CVE 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.
Integer Overflow to Buffer Overflow
Integer Overflow to Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.