Security readout for executives and security teams
Plain-English summary
GPAC 1.0.1 can corrupt memory when it opens a specially crafted MPEG-4 video. The user interaction requirement lowers urgency compared with a remote server bug, but organizations that process untrusted video should treat it seriously because the CVSS rating indicates possible confidentiality, integrity, and availability impact.
Executive priority
Prioritize remediation for any environment that accepts or processes external video content. For desktop-only exposure, handle through normal high-severity patching. For automated media pipelines, treat as more urgent because user-supplied files may be parsed at scale.
Technical view
The issue is an unchecked arithmetic integer overflow in GPAC MPEG-4 decoding for the “ctts” FOURCC path. The overflow can lead to a heap-based buffer overflow and memory corruption when a crafted MPEG-4 input is parsed. CVSS 3.0 is 8.8: network attack vector, low complexity, no privileges, user interaction required.
Likely exposure
Exposure is most likely where GPAC Project Advanced Content v1.0.1, or the listed commit, is installed and used to open or process MPEG-4 files from users, partners, uploads, or the internet. The bundle does not identify downstream applications beyond GPAC itself.
Exploitation context
The sources describe exploitation by convincing a user to open a crafted video. The CVE is not marked as CISA KEV in the bundle, and no cited source here states active exploitation in the wild.
Researcher notes
Track this as CWE-680 with heap buffer overflow consequences. The evidence supports malformed-file triggered memory corruption, not confirmed active exploitation. Avoid assuming exploitability beyond the CVSS impact and Talos description unless additional vendor or threat intelligence confirms it.
Mitigation direction
- Identify GPAC installations and versions in workstations, servers, containers, and media tooling.
- Apply GPAC or distribution updates referenced by vendor guidance, including Debian DSA-4966 where applicable.
- Avoid processing untrusted MPEG-4 files with affected GPAC versions until updated.
- Use sandboxing or isolation for media parsing workflows that must handle untrusted files.
Validation and detection
- Confirm whether GPAC Project Advanced Content v1.0.1 or the listed commit is present.
- Review package manager records for GPAC updates from your OS or vendor channel.
- Check media ingestion paths for user-supplied MPEG-4 parsing through GPAC.
- Verify controls prevent affected GPAC builds from handling untrusted video files.
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-2021-21836 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
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.