Answer in brief
CVE-2026-77220 records a High severity (CVSS 7.1) vulnerability in PDFio < 1.6.5 Dangling Pointer via Dictionary String-Formatting. The current sources do not mark it as known exploited. The current feed maps michaelrsweet/pdfio (generic), michaelrsweet/pdfio (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps michaelrsweet/pdfio (generic), michaelrsweet/pdfio (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| michaelrsweet/pdfiogeneric | * | Not reported |
| michaelrsweet/pdfiogeneric | >=0 <1.6.5 | 1.6.5 |
Published upstream
Aug 21, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 1, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 21, 2026
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.
Quoted source text, attributed separately from HOL analysis.