Security readout for executives and security teams
Plain-English summary
GPAC’s MPEG-4 parsing could be crashed or potentially hijacked by a malicious video file. The main business risk is systems or users processing untrusted MPEG-4 content with affected GPAC versions. The attack requires user interaction, but the impact rating is high.
Executive priority
Treat this as a high-priority remediation for media-processing systems, especially any workflow handling external video files. It is less urgent than a remotely exploitable server bug with known active exploitation, but affected exposed pipelines should not wait.
Technical view
CVE-2021-21846 is an integer overflow in GPAC MPEG-4 decoding, specifically the stsz decoder path. Unchecked arithmetic can lead to heap-based buffer overflow and memory corruption. Sources identify GPAC Project Advanced Content v1.0.1 and commit a8a8d412dabcb129e695c3e7d861fcc81f608304 as affected.
Likely exposure
Exposure is most likely where GPAC is installed directly, packaged by Linux distributions, or embedded in applications that parse MPEG-4 files. Workflows accepting uploaded, emailed, or downloaded videos deserve priority review.
Exploitation context
The CVSS vector indicates network-deliverable content, low attack complexity, no privileges required, and required user interaction. The bundle does not show CISA KEV listing or other evidence of active exploitation, so active exploitation should not be assumed.
Researcher notes
The core weakness is CWE-680: integer overflow to buffer overflow. Focus review on MPEG-4 parsing paths using GPAC, especially stsz handling. Evidence in the bundle supports memory corruption impact, but does not provide exploit-in-the-wild confirmation.
Mitigation direction
- Inventory GPAC installations and applications embedding GPAC media parsing.
- For Debian systems, follow DSA-4966 package guidance.
- Outside Debian, check GPAC or vendor guidance for fixed versions.
- Avoid processing untrusted MPEG-4 files with affected GPAC builds.
- Isolate media parsing workloads where practical.
Validation and detection
- Check installed GPAC versions against v1.0.1 and the affected commit.
- Review containers, packages, and application dependency manifests for GPAC use.
- Confirm Debian hosts have applied the DSA-4966 guidance.
- Identify services accepting user-supplied MPEG-4 content.
- Verify compensating isolation for unavoidable legacy media 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
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-2021-21846 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
- 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.