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


- **Severity:** Medium 4.1 (`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`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 29 Oct 2026
- **Updated:** 29 Oct 2026
- **Also known as:** GHSA-3448-gh8j-3227

## What is CVE-2026-118673?

CVE-2026-118673 is a medium-severity vulnerability in keepassxreboot keepassxc, published on 29 Oct 2026. 

### Official 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.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-118673?


## How do I fix CVE-2026-118673?

No fix has been published for CVE-2026-118673 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-118673 being exploited?

There is no known exploitation of CVE-2026-118673 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-118673 and fix it if it is affected.

What it is: CVE-2026-118673 is a medium-severity vulnerability in keepassxreboot keepassxc, published on 29 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-118673 in the wild and no public exploit code.

Affected product: keepassxreboot keepassxc. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-118673/ (Markdown: https://insights.sbomify.com/CVE-2026-118673/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-118673
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-118673
- OSV: https://osv.dev/vulnerability/CVE-2026-118673

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-118673/
Summaries are generated and may contain mistakes; the official description above is the record.