Sources: National Vulnerability Database, CVE.org, CISA KEV, FIRST EPSS
CVE-2026-120752 Overview
PyMuPDF 1.25.3 before 2.0 contains a stack-based buffer overflow vulnerability in JM_set_annot_callout_line() that copies a caller-supplied number of callout points into a fixed three-element stack array. Attackers who control the callout argument passed to Page.add_freetext_annot() can supply four or more points to overwrite the stack frame, crashing the process or executing code.
Critical Impact
Affected Products
- PyMuPDF: see the vendor advisory for the exact affected versions
Discovery Timeline
- 2026-11-02: CVE-2026-120752 published to the National Vulnerability Database by disclosure@vulncheck.com
- 2026-11-02: last updated in the NVD database
Technical Details for CVE-2026-120752
Vulnerability Analysis
CVE-2026-120752 is a Stack Buffer Overflow weakness (CWE-121: Stack Buffer Overflow) in PyMuPDF. Based on its CVSS vector, the flaw can be reached over the network, needs some level of access, and needs no user interaction. A write past the end of a stack buffer can corrupt control data.
With a CVSS base score of 7.7, apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Root Cause
The weakness is classified as CWE-121: Stack Buffer Overflow. A write past the end of a stack buffer can corrupt control data.
Attack Vector
Based on the CVSS vector, the flaw can be reached over the network, needs some level of access, and needs no user interaction. Attack complexity is low complexity.
No exploitation in the wild is confirmed by CISA at the time of the last update. Check the references below for any vendor or researcher proof of concept.
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/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
Detection Methods for CVE-2026-120752
Detection Strategies
- Inventory every instance of PyMuPDF and compare the running version with the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Run an authenticated vulnerability scan once your scanner ships a check for this CVE.
Monitoring Recommendations
- Forward PyMuPDF application, access and audit logs to your SIEM for retrospective hunting.
- Alert on new processes, configuration changes or outbound connections from the affected service.
- Track the vendor advisory and the CISA KEV catalog for changes in exploitation status.
How to Mitigate CVE-2026-120752
Immediate Actions Required
- Apply the fixed version of PyMuPDF named in the vendor advisory.
- Prioritize internet facing and business critical instances first.
- Rescan after the change to confirm the exposure is closed.
Patch Information
Use the fixed version listed in the vendor advisory for PyMuPDF.
Workarounds
- If patching must wait, restrict network access to the affected service and place it behind authentication or a web application firewall rule.
CWE References
- CWE-121: Stack Buffer Overflow More CVEs with this weakness
Technical References
This entry is built directly from NVD, CISA KEV and EPSS data. Verify fixed versions in the vendor advisory before you deploy.
Frequently asked questions
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