# CVE-2026-82465: pac4j-saml before 6.5.6 Session Destruction via Unsigned LogoutRequest

> An unauthenticated attacker can terminate a victim's SAML session by sending an unsigned LogoutRequest with a guessed identifier, causing denial of service.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 29 Aug 2026
- **Updated:** 31 Aug 2026
- **Also known as:** GHSA-r76c-m8xx-m685

## What is CVE-2026-82465?

CVE-2026-82465 is a medium-severity vulnerability in pac4j, published on 29 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

pac4j-saml before 6.5.6 does not require signature validation of SAML LogoutRequest messages in SAML2LogoutValidator.validateLogoutRequest(). When an IdP sends no SessionIndex, a session can be destroyed based solely on the NameID, allowing an unauthenticated attacker to submit an unsigned LogoutRequest with a guessed identifier (e.g., an email address used as NameID) to terminate a victim's SAML session.

Weakness: CWE-345 (Insufficient Verification of Data Authenticity)

## Which versions are affected by CVE-2026-82465?


## How do I fix CVE-2026-82465?

No fix has been published for CVE-2026-82465 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-82465 being exploited?

There is no known exploitation of CVE-2026-82465 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-82465 and fix it if it is affected.

What it is: CVE-2026-82465 is a medium-severity vulnerability in pac4j, published on 29 Aug 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-2026-82465 in the wild and no public exploit code.

Affected product: pac4j. 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-2026-82465/ (Markdown: https://insights.sbomify.com/CVE-2026-82465/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-82465
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-82465
- OSV: https://osv.dev/vulnerability/CVE-2026-82465

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-82465/
Summaries are generated and may contain mistakes; the official description above is the record.