PDFio < 1.6.5 Dangling Pointer via Dictionary String-Formatting
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- None · High · None
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA.
Summary
PDFio before 1.6.5 contains a dangling pointer vulnerability in the dictionary string-formatting function that stores a pointer to a stack-local buffer in the document dictionary without copying the string value. In multi-threaded or pooled-request environments, attackers or concurrent users can trigger stack memory reuse across requests, causing cross-tenant document content corruption by silently overwriting one caller's dictionary string values with another caller's data.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| michaelrsweet | pdfio | before 1.6.5 | 1.6.5 | Patch available | CNA |
- pdfio Vendormichaelrsweet Affected before 1.6.5 Fixed in 1.6.5 Patch available CNA
Remediation
- Fix · CNA pdfio (michaelrsweet) Fixed in 1.6.5
Timeline
- 2026-10-02 Threatist record created from CVE-2026-77220
- 2026-10-03 Alias added: GHSA-2fr4-jfvm-chmp
References
Patch 1
Other 1
More michaelrsweet vulnerabilities
- TI-2026-76283 Use after free in michaelrsweet mxml mxml_load_data CVSS 4.0MEDIUM 5.1
- TI-2026-74098 Off-by-one stack out-of-bounds write in Mini-XML mxml_strtod() CVSS 4.0LOW 2.0
Sources
- CVE-2026-77220 · CVE Program
- CVE-2026-77220 · NVD
- FIRST EPSS
- GHSA-2fr4-jfvm-chmp · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences