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.
https://www.vulncheck.com/advisories/pdfio-dangling-pointer-via-dictionary-string-formatting
https://github.com/michaelrsweet/pdfio/releases/tag/v1.6.5
https://github.com/michaelrsweet/pdfio/commit/22b9afc800c5833f9e851e35938972bd4c76a357
Published: 2026-08-21
Updated: 2026-08-21
Base Score: 6.8
Vector: CVSS2#AV:N/AC:L/Au:S/C:N/I:C/A:N
Severity: Medium
Base Score: 6.5
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Severity: Medium
Base Score: 7.1
Vector: 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
Severity: High
EPSS: 0.00239