CVE-2026-77220
MEDIUMDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 36% of all known CVEs.
References
Related Vulnerabilities
Other CWE-825 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-23638 | Medium | 6.5 | 60% | - | Fix |
| CVE-2026-33526 | High | 7.5 | 9.1% | - | Fix |
| CVE-2019-15691 | High | 7.2 | 4.7% | - | Fix |
| CVE-2023-48316 | Critical | 9.8 | 4.3% | - | Fix |
| CVE-2026-45447 | High | 8.8 | 4.0% | - | Fix |
| CVE-2023-48315 | High | 8.8 | 3.9% | - | Fix |
Common questions
How do I fix CVE-2026-77220?
Upgrade pdfio on debian unstable to 1.6.5+dfsg-1 or later.
Is CVE-2026-77220 being actively exploited?
Not that we know of. CVE-2026-77220 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.42% is the estimated probability that it will be exploited in the next 30 days. That is higher than 36% of all scored CVEs.
How severe is CVE-2026-77220?
CVE-2026-77220 has a CVSS v3 base score of 6.5, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-77220 affect?
Published advisories record a fix for pdfio (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-10-12.