# CVE-2026-77220

## Summary

- **CVE ID:** CVE-2026-77220
- **Severity:** HIGH
- **CVSS Score:** 7.1 (CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N)
- **CWE:** CWE-825
- **Published:** Aug 21, 2026
- **Last Modified:** Aug 24, 2026

## Description

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.

## Affected Products

- michaelrsweet — pdfio (0)

## References

- [CNA](https://github.com/michaelrsweet/pdfio/releases/tag/v1.6.5)
- [CNA](https://github.com/michaelrsweet/pdfio/commit/22b9afc800c5833f9e851e35938972bd4c76a357)
- [CNA](https://www.vulncheck.com/advisories/pdfio-dangling-pointer-via-dictionary-string-formatting)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.24%
- **EPSS Percentile:** 14.9

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-09._