Security readout for executives and security teams
Plain-English summary
GPAC’s MPEG-4 decoding can corrupt memory when processing a crafted video file. Successful exploitation requires a user or media workflow to open the malicious MPEG-4 input, but impact is severe: confidentiality, integrity, and availability are all rated high.
Executive priority
Treat as high priority for media-processing environments and any endpoint where users open external video files. The required user interaction lowers urgency versus wormable bugs, but memory corruption in a parser creates meaningful business risk.
Technical view
CVE-2021-21850 is an unchecked arithmetic integer overflow in GPAC Project Advanced Content v1.0.1 and commit a8a8d412. A crafted MPEG-4 atom using the “trun” FOURCC can trigger a heap-based buffer overflow during decoding, causing memory corruption.
Likely exposure
Exposure is most likely where GPAC or libgpac is installed to inspect, transcode, package, or preview MPEG-4 media. Debian systems with affected GPAC packages are specifically referenced by DSA-4966. Evidence provided does not identify other affected products.
Exploitation context
The CVSS vector is network-adjacent in practical delivery terms because the malicious file can be supplied remotely, but user interaction is required. The source bundle does not show CISA KEV listing or active exploitation evidence.
Researcher notes
Primary evidence points to CWE-680: integer overflow leading to heap buffer overflow. Focus validation on GPAC MPEG-4 decoding paths and “trun” atom handling. Do not assume active exploitation; provided sources describe exploitability, not in-the-wild use.
Mitigation direction
- Apply GPAC or distribution security updates from official vendor guidance.
- For Debian systems, follow DSA-4966 package update guidance.
- Limit processing of untrusted MPEG-4 files until affected GPAC builds are remediated.
- Review media upload and preview workflows that invoke GPAC.
- Monitor vendor advisories for any additional backported fixes.
Validation and detection
- Inventory systems and containers for GPAC Project Advanced Content v1.0.1.
- Check whether commit a8a8d412 or affected libgpac builds are present.
- Confirm Debian hosts have applied DSA-4966 updates where relevant.
- Map services that automatically process user-supplied MPEG-4 media.
- Verify compensating controls restrict untrusted media processing on unpatched systems.
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-2021-21850 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.
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.