---
id: CVE-2026-115758
title: 'SumatraPDF: TLS hostname validation disabled in `HttpGet()`'
summary: >-
  SumatraPDF is a multi-format reader for Windows. In version 3.6.1 and earlier,
  HttpGet() in src/base/Http_win.cpp unconditionally passes
  INTERNET_FLAG_IGNORE_CERT_CN_INVALID to WinINet, disabling hostname matching
  for HTTPS update metada…
severity: high
cvss: 8.2
cvssVector: 'CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N'
cvssSource: cna
cwe:
  - CWE-297
vendor: sumatrapdfreader
product: sumatrapdf
affected:
  - sumatrapdf <= 3.6.1
published: '2026-11-04'
updated: '2026-11-04'
sourceUpdated: '2026-11-04T20:44:55.316Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-115758'
references:
  - url: >-
      https://github.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-mjwr-9w29-jp96
    label: >-
      https://github.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-mjwr-9w29-jp96
  - url: >-
      https://github.com/sumatrapdfreader/sumatrapdf/commit/bd30134175e897dd5ed0d7fd14acce52eeca7183
    label: >-
      https://github.com/sumatrapdfreader/sumatrapdf/commit/bd30134175e897dd5ed0d7fd14acce52eeca7183
tags:
  - cve.org
ingestedAt: '2026-11-05T21:36:00.571Z'
epss: 0.00145
epssPercentile: 0.03792
---

## Overview

SumatraPDF is a multi-format reader for Windows. In version 3.6.1 and earlier, HttpGet() in src/base/Http_win.cpp unconditionally passes INTERNET_FLAG_IGNORE_CERT_CN_INVALID to WinINet, disabling hostname matching for HTTPS update metadata and crash-symbol requests while retaining certificate-chain validation. A network-positioned attacker with a Windows-trusted certificate for an attacker-controlled domain can impersonate the project's update host, inject promo text and a clickable URL before update metadata validation, and provide an attacker-controlled archive to ExtractSymbols(). Installer replacement is not directly possible because HttpGetToFile() validates TLS and MaybeStartUpdateDownload() restricts the download host. No fixed version is available as of this review.

## Affected

- `sumatrapdf <= 3.6.1`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.