Security readout for executives and security teams
Plain-English summary
CVE-2021-21840 is a high-severity flaw in GPAC media parsing. A malicious MPEG-4 file can corrupt memory when opened, creating risk of code execution or service compromise where GPAC processes untrusted videos.
Executive priority
Treat this as a near-term patching and exposure-reduction item for systems handling outside media. Business urgency is highest for video upload, transcoding, and review workflows that process files from untrusted parties.
Technical view
GPAC Project Advanced Content v1.0.1 and commit a8a8d412 contain unchecked arithmetic while decoding an MPEG-4 atom with the saio FOURCC. The integer overflow can become a heap-based buffer overflow and memory corruption. CVSS is 8.8, with user interaction required.
Likely exposure
Exposure is most likely where GPAC or libgpac parses MPEG-4 files from users, partners, web uploads, email attachments, or automated media workflows. The bundle only names GPAC Project Advanced Content v1.0.1 and one commit.
Exploitation context
The source bundle says an attacker must convince a user to open a crafted video. It does not cite CISA KEV listing or active exploitation, so active exploitation should not be assumed.
Researcher notes
The evidence supports memory corruption from integer overflow leading to heap overflow. The bundle does not provide proof of in-the-wild exploitation, a complete affected-version range, or detailed fixed-version information beyond vendor advisory references.
Mitigation direction
- Identify all GPAC and libgpac deployments and package sources.
- Prioritize updating GPAC packages using vendor guidance, including Debian DSA-4966 where applicable.
- Restrict GPAC processing of untrusted MPEG-4 files until patched.
- Run media parsing workloads with least privilege and isolation.
- Check upstream GPAC and distribution advisories for fixed versions.
Validation and detection
- Confirm installed GPAC versions against v1.0.1 and the named commit.
- Map applications and services that invoke GPAC for MPEG-4 parsing.
- Verify Debian or other distribution security updates are installed.
- Review crash telemetry for GPAC MPEG-4 parsing memory faults.
- Confirm upload pipelines reject or sandbox untrusted video processing.
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
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CWE-680: Exact CWE lookup
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Open ATT&CK lookupCVE-2021-21840 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.