---
id: CVE-2026-118673
title: >-
  KeePassXC: Out-of-bounds write in browser integration response encryption with
  oversized database responses
summary: >-
  KeePassXC is a cross-platform community-driven port of the Windows application
  KeePass Password Safe. From 2.3.0 until 2.8.0, KeePassXC browser integration
  encrypts authorized responses in src/browser/BrowserMessageBuilder.cpp using a
  fi…
severity: medium
cvss: 4.1
cvssVector: 'CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'
cvssSource: cna
cwe:
  - CWE-787
vendor: keepassxreboot
product: keepassxc
affected:
  - 'keepassxc >= 2.3.0, < 2.8.0'
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-03T16:30:40.960267Z'
exploitAvailable: true
published: '2026-10-29'
updated: '2026-11-03'
sourceUpdated: '2026-11-03T16:32:32.671Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-118673'
references:
  - url: >-
      https://github.com/keepassxreboot/keepassxc/security/advisories/GHSA-3448-gh8j-3227
    label: >-
      https://github.com/keepassxreboot/keepassxc/security/advisories/GHSA-3448-gh8j-3227
  - url: 'https://github.com/keepassxreboot/keepassxc/pull/13679'
    label: 'https://github.com/keepassxreboot/keepassxc/pull/13679'
  - url: >-
      https://github.com/keepassxreboot/keepassxc/commit/80e68bb4e8b89e383dd96b1bf5de169ca61367aa
    label: >-
      https://github.com/keepassxreboot/keepassxc/commit/80e68bb4e8b89e383dd96b1bf5de169ca61367aa
  - url: 'https://github.com/keepassxreboot/keepassxc/releases/tag/2.8.0'
    label: 'https://github.com/keepassxreboot/keepassxc/releases/tag/2.8.0'
tags:
  - cve.org
  - exploit-available
epss: 0.00115
epssPercentile: 0.01554
ingestedAt: '2026-11-01T21:01:32.726Z'
---

## Overview

KeePassXC is a cross-platform community-driven port of the Windows application KeePass Password Safe. From 2.3.0 until 2.8.0, KeePassXC browser integration encrypts authorized responses in src/browser/BrowserMessageBuilder.cpp using a fixed 1 MiB output vector even though Botan::Sodium::crypto_box_easy() writes the plaintext length plus crypto_box_MACBYTES. A browser-protocol client that can access the per-user IPC endpoint, has a valid database association, and causes an unlocked database to generate and encrypt a sufficiently large authorized response can trigger a sequential out-of-bounds write before any response is delivered. This issue is fixed in version 2.8.0.

## Affected

- `keepassxc >= 2.3.0, < 2.8.0`

## Remediation

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