Security readout for executives and security teams
Plain-English summary
FAAD2 had a memory safety flaw where overly long filename or pathname options could overflow a stack buffer. A local attacker who can run the FAAD2 frontend or influence those options may be able to execute code on that system.
Executive priority
Treat this as a focused local-code-execution risk. Prioritize shared systems, appliances, media-processing hosts, and build environments where untrusted users or files may reach faad2.
Technical view
CVE-2021-26567 is a CWE-121 stack-based buffer overflow in frontend/main.c in faad2 before 2.2.7.1. The reported trigger is filename and pathname options. The source bundle states local attackers can execute arbitrary code.
Likely exposure
Exposure is most likely on systems with faad2 before 2.2.7.1 installed, or products that bundle that code. The provided sources do not establish internet-facing exploitation.
Exploitation context
The bundle reports local attack context and arbitrary code execution potential. It is not listed as CISA KEV, and the provided sources do not claim active exploitation.
Researcher notes
Evidence is limited to the CVE description, the upstream commit reference, and a Synology advisory reference. No CVSS vector, detailed exploit preconditions, or active exploitation evidence is included in the bundle.
Mitigation direction
- Upgrade faad2 to 2.2.7.1 or later where available.
- Apply downstream vendor updates for products bundling faad2.
- Limit local shell or job execution access to trusted users.
- Avoid passing untrusted filename or pathname values to faad2 until patched.
Validation and detection
- Inventory installed faad2 versions and bundled copies.
- Confirm any faad2 instance is 2.2.7.1 or later.
- Review vendor advisories for appliances or packages using faad2.
- Check workflows for untrusted filename or pathname input to faad2.
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-121: 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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-26567 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://www.synology.com/security/advisory/Synology_SA_20_26CVE reference · x_refsource_CONFIRM
- https://github.com/knik0/faad2/commit/720f7004d6c4aabee19aad16e7c456ed76a3ebfaCVE 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.
Stack-based Buffer Overflow
Stack-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.