Security readout for executives and security teams
Plain-English summary
GPAC can mishandle specially crafted MPEG-4 video content, causing memory corruption when a user or service opens the file. The impact can include data exposure, tampering, or service disruption. The sources do not show CISA KEV listing or confirmed active exploitation.
Executive priority
Treat as a high-priority media parsing risk if GPAC handles external video files. Business urgency is highest for public upload, transcoding, or preview services. If GPAC is absent, exposure is unlikely.
Technical view
CVE-2021-21843 is an integer overflow in GPAC Advanced Content v1.0.1 MPEG-4 decoding. Unchecked arithmetic when sizing GF_SubsegmentRangeInfo arrays can under-allocate memory on 32-bit platforms, leading to heap-based buffer overflow and memory corruption. Exploitation requires crafted MPEG-4 input and user interaction.
Likely exposure
Exposure is most likely where GPAC or libgpac processes untrusted MPEG-4 files, including media upload, transcoding, preview, or user playback workflows. Affected sources name GPAC Advanced Content v1.0.1 and commit a8a8d412dabcb129e695c3e7d861fcc81f608304.
Exploitation context
The CVSS vector indicates network delivery is possible, no privileges are required, and user interaction is required. A cited Talos report describes convincing a user to open a crafted video. No provided source confirms active exploitation in the wild.
Researcher notes
The key technical condition is unchecked multiplication after range-count validation, producing under-allocation and heap corruption on 32-bit platforms. Evidence supports crafted-file exploitation with user interaction, but the bundle lacks detailed fixed-version data beyond referenced advisories.
Mitigation direction
- Check GPAC and distribution advisories for fixed packages or recommended updates.
- Update affected GPAC or libgpac builds where vendor guidance provides patched versions.
- Limit GPAC processing of untrusted MPEG-4 files until remediation is confirmed.
- Prioritize 32-bit builds and internet-facing media processing workflows.
- Use sandboxing or isolation for media parsing where immediate update is unavailable.
Validation and detection
- Inventory systems and applications using GPAC or libgpac MPEG-4 decoding.
- Confirm whether GPAC Advanced Content v1.0.1 or the affected commit is present.
- Check Debian or vendor package status against the cited advisory.
- Identify workflows that accept MPEG-4 files from users or external parties.
- Verify remediation through package metadata, SBOMs, or vendor release evidence.
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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Open ATT&CK lookupCVE-2021-21843 mapping review
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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
- https://www.talosintelligence.com/vulnerability_reports/TALOS-2021-1297CVE reference · x_refsource_MISC
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.