CVE-2026-84311
MEDIUMDescription
pypdf is a free and open-source pure-python PDF library. Prior to 6.16.1, an attacker can craft a PDF that causes pypdf/_page.py PageObject._extract_text and PageObject.extract_xform_text to traverse a directed acyclic graph of reused form XObjects in which each form invokes a child multiple times, creating exponentially many traversal paths and causing long runtimes and large memory consumption. This issue is fixed in version 6.16.1.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v4 Vector
Exploitability
Impact
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Exploit Intelligence
Low risk: more likely to be exploited than 4% of all known CVEs.
References
Related Vulnerabilities
Other CWE-834 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2021-35515 | High | 7.5 | 12% | - | Fix |
| CVE-2021-39924 | High | 7.5 | 5.1% | - | Fix |
| CVE-2023-1993 | Medium | 6.3 | 4.1% | - | Fix |
| CVE-2018-14342 | High | 7.5 | 3.7% | - | Fix |
| CVE-2020-14303 | High | 7.5 | 3.5% | - | Fix |
| CVE-2018-11813 | High | 7.5 | 3.2% | - | Fix |
Common questions
How do I fix CVE-2026-84311?
No published fix for CVE-2026-84311 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-84311 being actively exploited?
Not that we know of. CVE-2026-84311 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.14% is the estimated probability that it will be exploited in the next 30 days. That is higher than 4% of all scored CVEs.
How severe is CVE-2026-84311?
CVE-2026-84311 has a CVSS v4 base score of 4.8, 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.
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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 2026-09-09.