Security readout for executives and security teams
Plain-English summary
A malicious MPEG-4 video can crash or corrupt memory in vulnerable GPAC decoding code when opened or processed. The business risk is highest where GPAC handles untrusted video files, such as media ingestion workflows or user-submitted content.
Executive priority
Treat as high priority for media-heavy environments or any system processing untrusted video. For organizations without GPAC or MPEG-4 ingestion exposure, urgency is lower but still requires inventory confirmation.
Technical view
CVE-2021-21861 is an integer truncation in GPAC Project Advanced Content v1.0.1, including commit a8a8d412dabcb129e695c3e7d861fcc81f608304. Processing an MPEG-4 hdlr FOURCC can cause improper allocation and heap-based buffer overflow, leading to memory corruption.
Likely exposure
Exposure is likely limited to systems, applications, or Linux packages that include the affected GPAC Advanced Content code and parse MPEG-4 files from users or external sources.
Exploitation context
The source bundle says an attacker must convince a user to open a crafted video. KEV is false, and the provided sources do not establish active exploitation in the wild.
Researcher notes
The vulnerability maps to CWE-680 and CVSS 3.0 score 8.8. The key technical condition is MPEG-4 hdlr handling causing integer truncation, under-allocation, then heap overflow. Do not assume active exploitation from the supplied evidence.
Mitigation direction
- Inventory GPAC usage in applications, packages, containers, and media-processing pipelines.
- Apply relevant vendor or distribution updates, including Debian DSA-4966 where applicable.
- Check GPAC vendor guidance for the fixed version or recommended workaround.
- Avoid processing untrusted MPEG-4 files with vulnerable GPAC builds.
- Run media parsing workloads with sandboxing and least privilege.
Validation and detection
- Confirm installed GPAC versions are not v1.0.1 or the affected commit.
- Check Debian package status against DSA-4966 if using Debian packages.
- Review services that automatically parse uploaded or emailed MPEG-4 files.
- Test that untrusted media processing runs under restricted permissions.
- Verify update evidence in SBOMs, package manifests, or deployment records.
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-2021-21861 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
- 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.
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.