# CVE-2026-56091: Apache Shiro: Authentication bypass in Guice-Web integration

> Attackers can bypass authentication in Apache Shiro web applications using the shiro-guice module via crafted HTTP requests.

- **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/S:P/AU:Y/V:D/RE:L/U:Amber`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 25 Jun 2026
- **Updated:** 25 Jun 2026
- **Also known as:** DEBIAN-CVE-2026-56091, GHSA-qj64-jj84-w38j, UBUNTU-CVE-2026-56091

## What is CVE-2026-56091?

CVE-2026-56091 is a high-severity authentication bypass vulnerability in Apache Shiro, published on 25 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

When using Apache Shiro with the shiro-guice module in a web servlet context, a specially crafted HTTP request may cause an authentication bypass.
This vulnerability is similar to  https://www.cve.org/CVERecord?id=CVE-2020-1957 https://www.cve.org/CVERecord , except that it affects the `shiro-guice` module instead of the `shiro-spring` module.

This issue affects all Apache Shiro versions through 2.x, and 3.0.0-alpha-1 only when using `shiro-guice` module in a web servlet context.

Upgrade to version 3.0.0 or later, which fixes the issue.

Weakness: CWE-289 (Authentication Bypass by Alternate Name)

## Which versions are affected by CVE-2026-56091?


## How do I fix CVE-2026-56091?

No fix has been published for CVE-2026-56091 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-56091 being exploited?

There is no known exploitation of CVE-2026-56091 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-56091 and fix it if it is affected.

What it is: CVE-2026-56091 is a high-severity authentication bypass vulnerability in Apache Shiro, published on 25 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-56091 in the wild and no public exploit code.

Affected product: Apache Shiro. 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-2026-56091/ (Markdown: https://insights.sbomify.com/CVE-2026-56091/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-56091
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-56091
- OSV: https://osv.dev/vulnerability/CVE-2026-56091

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-56091/
Summaries are generated and may contain mistakes; the official description above is the record.