Security readout for executives and security teams
Plain-English summary
CVE-2021-33815 is a memory-safety flaw in FFmpeg 4.4 when decompressing EXR content. A specially crafted media file could trigger out-of-bounds array access. The provided sources do not state business impact, CVSS severity, or confirmed exploitation, so urgency depends on whether FFmpeg processes untrusted EXR files in your environment.
Executive priority
Treat this as a targeted media-processing risk, not a confirmed emergency. Patch promptly where FFmpeg handles untrusted EXR content; otherwise track through normal vulnerability management until vendor guidance confirms severity and remediation status.
Technical view
The issue is in dwa_uncompress in libavcodec/exr.c. The CVE states dc_count is not strictly checked, allowing out-of-bounds array access in FFmpeg 4.4. The source bundle references an upstream FFmpeg commit and a Gentoo advisory, but does not provide CVSS, CWE classification, or detailed exploitation impact.
Likely exposure
Exposure is most likely where FFmpeg 4.4 decodes EXR media, especially in upload, rendering, transcoding, thumbnailing, or media-processing workflows that accept files from users or partners.
Exploitation context
The source bundle marks KEV as false and provides no cited evidence of active exploitation. The plausible risk is malicious or malformed EXR input reaching FFmpeg, but exploitability and impact are not fully described in the provided sources.
Researcher notes
Key evidence is limited to the CVE description, upstream FFmpeg commit, and Gentoo advisory. Do not assume broader affected versions, active exploitation, or specific impact beyond out-of-bounds array access unless confirmed by vendor analysis.
Mitigation direction
- Inventory FFmpeg and libavcodec versions in media-processing systems.
- Prioritize systems that process untrusted EXR files.
- Apply vendor or distribution updates that include the FFmpeg fix.
- For Gentoo systems, follow GLSA-202312-14 guidance.
- Temporarily restrict untrusted EXR processing where patching is delayed.
Validation and detection
- Confirm whether FFmpeg 4.4 is installed or bundled.
- Check whether the upstream fix commit is present in the package.
- Review applications that invoke FFmpeg on uploaded or external files.
- Verify patched packages through vendor release notes or advisories.
- Document remaining systems that cannot be updated promptly.
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.
CVE-2021-33815 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
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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 and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/FFmpeg/FFmpeg/commit/26d3c81bc5ef2f8c3f09d45eaeacfb4b1139a777CVE reference
- GLSA-202312-14CVE 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.