Security readout for executives and security teams
Plain-English summary
CVE-2021-21845 is a high-severity flaw in GPAC's MPEG-4 handling. A malicious video file can trigger memory corruption when opened, potentially affecting confidentiality, integrity, and availability. Business risk is highest where GPAC processes untrusted media from users, partners, email, web uploads, or automated pipelines.
Executive priority
Prioritize remediation where GPAC touches untrusted video content. This is not evidenced as actively exploited in the supplied sources, but the impact is high and the trigger fits common file-processing workflows.
Technical view
GPAC Project Advanced Content v1.0.1 contains unchecked arithmetic in the MPEG-4 “stsc” decoder. A crafted MPEG-4 input can cause integer overflow leading to heap-based buffer overflow and memory corruption. CVSS 3.0 is 8.8 with required user interaction and no privileges required.
Likely exposure
Exposure is likely limited to systems, applications, or distributions using GPAC Project Advanced Content v1.0.1 or the cited vulnerable commit to decode MPEG-4 content. Media upload, transcoding, preview, forensic, or desktop playback workflows are the main places to check.
Exploitation context
The source bundle does not show CISA KEV listing or active exploitation evidence. Exploitation requires a specially crafted MPEG-4 and a user or automated process opening it. Treat internet-sourced media processing as higher risk because attacker-controlled files are plausible.
Researcher notes
Key evidence comes from the CVE record, Talos advisory TALOS-2021-1297, and Debian DSA-4966. The bundle identifies CWE-680 and heap-based memory corruption but does not provide enough evidence to claim exploitation in the wild or universal product impact beyond GPAC.
Mitigation direction
- Inventory GPAC usage, including embedded media processing and transcode pipelines.
- Upgrade vulnerable GPAC packages per GPAC or distribution vendor guidance.
- For Debian-managed systems, review and apply DSA-4966 guidance.
- Restrict untrusted MPEG-4 processing until affected GPAC components are remediated.
- Run media decoding in sandboxed or least-privileged environments where feasible.
Validation and detection
- Check installed GPAC versions against v1.0.1 and the cited vulnerable commit.
- Identify services or desktops that process untrusted MPEG-4 files.
- Confirm Debian hosts have incorporated DSA-4966 updates where applicable.
- Review software bills of materials for bundled GPAC libraries.
- Verify compensating controls around media upload and decoding paths.
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-2021-21845 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
- DSA-4966CVE reference · vendor-advisory, x_refsource_DEBIAN
- 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.