CVE-2026-107731

SumatraPDF before version 3.6 has a vulnerability in the MobiDoc::ParseHeader function, where the decoder is sized for a fixed length rather than the actual buffer length. A malformed MOBI file can cause a read beyond a short heap buffer, leading to application crash.

SumatraPDF 3.6.1 and earlier embeds selected or pasted translation text in quoted Windows command lines in src/SelectionTranslate.cpp using incomplete quote-only escaping. The affected BuildGrokTranslateCmdLineTemp(), BuildClaudeTranslateCmdLineTemp(), and BuildCodexTranslateCmdLineTemp() functions can allow attacker-controlled text to inject model, working-directory, approval, or sandbox-bypass flags when the corresponding agentic CLI backend is installed and used.

SumatraPDF 3.6.1 and earlier has a vulnerability in ChmFile::GetCharZ() where file-controlled unsigned offsets are narrowed to signed integers without a lower-bound check. This can cause reads before the /#STRINGS buffer and deterministic application termination.

SumatraPDF 3.6.1 and earlier, and pre-release 3.7.0.20369 when WebView2 is absent, has a vulnerability in ParseProtoUrl() where the signed host component of an its:// URL is used as an index into gHtmlWindows. This can cause out-of-bounds pointer read and invalid callback dereference, terminating the process.

SumatraPDF 3.6.1 and earlier has a vulnerability in MaybeFlipBitmap() where GDI+ reads the attacker-controlled PropertyTagOrientation size into a fixed 64-byte stack buffer. Opening a crafted TIFF can overwrite stack control data, though tested builds terminate via stack cookie check.

SumatraPDF 3.6.1 and earlier has a vulnerability in InitializePolicies() where the sumatrapdfrestrict.ini path starts with gPolicyRestrictions set to Perm::All and only ORs permission bits, so the INI file never revokes permissions. Deploying with this INI file, including malformed or zero-valued settings, can silently bypass configured disk, network, printing, registry, clipboard, preference, and fullscreen restrictions.

SumatraPDF 3.5.2 and earlier substitutes an attacker-controlled SyncTeX source filename for the %f placeholder in an external editor command line without safe Windows argument quoting, and the resulting command line is passed to CreateProcessW(). A user with an external editor configured or auto-detected who opens a PDF with a crafted .synctex.gz file and invokes inverse search can inject command-line flags.

SumatraPDF 3.6.1 and earlier has a vulnerability in FrameOnCommand() where CmdExec passes a null current-tab pointer to RunWithExe(), which dereferences WindowTab::filePath. A local process in the same interactive Windows session, at an integrity level greater than or equal to SumatraPDF's, can dispatch CmdExec over DDE or WM_COPYDATA while no document tab is open, causing abrupt process termination and loss of unsaved state.

SumatraPDF 3.6.1 and earlier interpolates untrusted document paths and PDF link targets into notification text that ParseTip() interprets as trusted tip markup. When a user clicks an injected link, ExecuteTipLink() dispatches its CmdExec command and can execute an attacker-selected local program in the user's context.

SumatraPDF 3.7.0.22298 has a vulnerability in LitParseHeader() in src/LitDoc.cpp where the attacker-controlled hdrLen + nPieces * 16 section offset is computed using signed 32-bit arithmetic without validating the complete result. When the aggregate calculation overflows to a negative value, pointer construction reaches an invalid read in LitU32(), causing deterministic application termination.