Security readout for executives and security teams
Plain-English summary
CVE-2021-21852 is a memory-corruption flaw in GPAC’s MPEG-4 parsing. A malicious video can trigger an integer overflow and heap buffer overflow when opened. Impact can include compromise of confidentiality, integrity, and availability, but user interaction or an automated media-processing workflow is required.
Executive priority
Treat as high priority where GPAC processes external media, especially in automated upload, transcoding, or content-inspection services. User interaction lowers broad urgency, but high impact makes remediation important.
Technical view
Talos describes unchecked arithmetic in GPAC Project Advanced Content v1.0.1 MPEG-4 “stss” decoding, leading to integer overflow and heap-based buffer overflow. The CVSS vector is network-reachable with low complexity, no privileges, user interaction required, and high CIA impact.
Likely exposure
Exposure is most likely on endpoints, servers, or applications that use GPAC/libgpac to open, inspect, transcode, index, or otherwise process MPEG-4 files from untrusted sources.
Exploitation context
The source bundle does not show CISA KEV listing or other evidence of active exploitation. Exploitation requires convincing a user, or a media-processing pipeline, to process a specially crafted MPEG-4 file.
Researcher notes
Evidence supports an integer-overflow-to-heap-overflow chain in MPEG-4 “stss” decoding. The affected data in the bundle is imprecise, so confirm exact package names and fixed versions from Talos and vendor advisories before scoping.
Mitigation direction
- Identify GPAC/libgpac installations and bundled dependencies.
- Apply vendor or distribution security updates, including Debian DSA-5411 where applicable.
- Restrict untrusted MPEG-4 processing until patched.
- Run media parsers with least privilege and sandboxing where feasible.
- Monitor vendor guidance for exact fixed versions.
Validation and detection
- Confirm installed GPAC/libgpac versions against vendor advisories.
- Inventory applications that bundle or dynamically link GPAC.
- Review media ingestion paths for untrusted MPEG-4 handling.
- Check endpoint and server telemetry for GPAC package presence.
- Verify patched systems no longer run affected builds.
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
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ATT&CK lookup starting points
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CWE-680: Exact CWE lookup
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Open ATT&CK lookupCVE-2021-21852 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
- https://www.talosintelligence.com/vulnerability_reports/TALOS-2021-1297CVE reference
- DSA-5411CVE reference · vendor-advisory
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.