Security readout for executives and security teams
Plain-English summary
This flaw is in GPAC's MPEG-4 decoding. A malicious video can trigger memory corruption when opened by a vulnerable application. The likely business risk is compromise of systems or users that process untrusted video, with potential confidentiality, integrity, and availability impact.
Executive priority
Treat this as high priority for media-handling environments. The issue can affect confidentiality, integrity, and availability, but requires a vulnerable decoder and malicious video handling. Prioritize internet-facing or user-upload workflows first.
Technical view
CVE-2021-21837 is a CWE-680 integer overflow in GPAC Project Advanced Content v1.0.1 and commit a8a8d412. Unchecked arithmetic in MPEG-4 decoding can lead to heap-based buffer overflow and memory corruption. CVSS 3.0 score is 8.8 with user interaction required.
Likely exposure
Exposure is most likely where GPAC or applications embedding GPAC decode MPEG-4 files from users, partners, the internet, or email attachments. The source bundle names GPAC Project Advanced Content v1.0.1 and one commit; it does not prove other versions are affected.
Exploitation context
The sources describe a specially crafted MPEG-4 file and a need to convince a user to open the video. The bundle does not cite CISA KEV or any active exploitation evidence, so active exploitation should not be assumed.
Researcher notes
Focus validation on version and code provenance, not just package names. The evidence names GPAC Advanced Content v1.0.1 and a specific commit. The source bundle does not include fixed upstream versions, proof of exploitation, or safe detection artifacts.
Mitigation direction
- Inventory GPAC and embedded GPAC libraries in media-processing systems.
- Prioritize systems that open or ingest untrusted MPEG-4 content.
- Check GPAC and distribution advisories for fixed packages or vendor guidance.
- Apply trusted vendor or distribution updates where available.
- Restrict untrusted video processing until vulnerable components are remediated.
Validation and detection
- Confirm whether GPAC Project Advanced Content v1.0.1 is present.
- Identify applications that embed GPAC rather than installing it as a package.
- Review media ingestion paths for user-supplied MPEG-4 files.
- Verify patched package status against Debian DSA-4966 or vendor guidance.
- Document compensating controls for systems that cannot be upgraded promptly.
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-2021-21837 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.