# CVE-2026-77220: pdfio: PDFio before 1.6.5 contains a dangling pointer vulnerability in the dictionary string-formatting function that stores...

CVE-2026-77220 is fixed in pdfio on 1 platform by DEBIAN-CVE-2026-77220 (version 1.6.5+dfsg-1), released September 7, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-77220
- Priority: Routine
- CVSS: n/a
- EPSS: 0.0042
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 21, 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | pdfio Debian 14 | 1.6.5+dfsg-1 | [DEBIAN-CVE-2026-77220](https://patchblox.com/security/data/fix/linux/debian-cve-2026-77220.md) | Sep 7, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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