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CVE-2026-77220— PDFio < 1.6.5 Dangling Pointer via Dictionary String-Formatting

Quick assessment

Affected
michaelrsweet pdfio
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

PDFio 版本在 1.6.5 之前存在一个悬空指针漏洞，该漏洞位于用于字典字符串格式化的函数中。该函数将指向栈上局部缓冲区的指针存储到文档字典中，而没有复制字符串值本身。在多线程或请求池化的环境中，攻击者或并发用户可能触发栈内存在不同请求间的复用，从而导致跨租户的文档内容被损坏——即一个调用者的字典字符串值会被另一个调用者的数据静默覆盖。

CVSS 6.5 · Medium EPSS 0.24% · P15

Affected Version Matrix 1

VendorProduct Version RangeStatus
michaelrsweet pdfio < 1.6.5 affected
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I. Basic Information for CVE-2026-77220

Vulnerability Information
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Vulnerability Title
PDFio < 1.6.5 Dangling Pointer via Dictionary String-Formatting
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
无效指针解引用
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
michaelrsweet pdfio 0 ~ 1.6.5 -

II. Public POCs for CVE-2026-77220

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III. Intelligence Information for CVE-2026-77220

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Patches & Fixes for CVE-2026-77220 (1)

Vendor Advisories for CVE-2026-77220 (1)

Vendor Pages for CVE-2026-77220 (1)

IV. Related Vulnerabilities

Same product: pdfio
Same vendor: michaelrsweet
Same weakness: CWE-825

V. Comments for CVE-2026-77220

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