Security readout for executives and security teams
Plain-English summary
SumatraPDF for Windows 3.5.2 and earlier can start the wrong notepad.exe when Advanced Options is used. If an attacker can place a malicious file named notepad.exe in the SumatraPDF installation folder, opening Advanced Options could run attacker code. This is high impact but requires local file placement and user interaction.
Executive priority
Prioritize remediation in managed Windows fleets where SumatraPDF is installed broadly or users can write to application folders. This is high severity code execution, but not remotely exploitable by itself based on the sources. Treat as a near-term endpoint hardening and software update task, not an internet-facing emergency.
Technical view
CVE-2026-23512 is a CWE-426 untrusted search path issue in sumatrapdf/src/AppTools.cpp. The application launches notepad.exe without an absolute path when Advanced Options is triggered. Windows search behavior can prefer a malicious notepad.exe in the application directory, causing arbitrary code execution. CVSS is 8.6, local attack vector, low complexity, no privileges, user interaction required.
Likely exposure
Windows endpoints running SumatraPDF 3.5.2 or earlier. Risk is higher where the installation directory is user-writable, loosely managed, or contains unexpected executables. Systems without SumatraPDF, or with later versions not covered by the advisory, are not indicated as affected by the provided sources.
Exploitation context
The provided sources do not indicate active exploitation, and the CVE is not listed as KEV in the bundle. Exploitation requires a malicious notepad.exe to be present in SumatraPDF’s installation directory and a user to trigger Advanced Options. This is more plausible after prior local access, social engineering, or weak directory permissions.
Researcher notes
The key condition is path resolution for notepad.exe from Advanced Options. Validate only in controlled environments and avoid publishing weaponized procedures. The source bundle identifies the vulnerable file and fixing commit, but does not state a specific fixed release. Do not assume exploitation in the wild without additional evidence.
Mitigation direction
- Inventory SumatraPDF installations and identify versions 3.5.2 or earlier.
- Check vendor advisory and commit for the official remediation path.
- Upgrade or replace affected installations according to vendor guidance.
- Ensure SumatraPDF installation directories are not writable by standard users.
- Remove unexpected notepad.exe files from SumatraPDF installation directories.
- Limit use of Advanced Options on affected systems until remediated.
Validation and detection
- Confirm installed SumatraPDF version on Windows endpoints.
- Review the SumatraPDF installation directory permissions.
- Inspect installation directories for unexpected notepad.exe files.
- Verify remediation against the vendor advisory or fixed source commit.
- Monitor endpoint alerts for suspicious executables launched from SumatraPDF directories.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-426: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-23512 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.6 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H1.86Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.6HighVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-rqg5-gj63-x4mvCVE reference · x_refsource_CONFIRM
- https://github.com/sumatrapdfreader/sumatrapdf/commit/2762e02a8cd7cb779c934a44257aac56ab7de673CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Untrusted Search Path
Untrusted Search Path represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.