# CVE-2026-66400: Grav Login Plugin before 3.8.13 Insufficient Session Expiration

> Attackers with a captured Remember Me cookie can maintain indefinite access due to flawed token expiration logic in the Grav Login Plugin.

- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/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 Jul 2026
- **Updated:** 29 Jul 2026
- **Also known as:** GHSA-x4cg-fxgx-67gm

## What is CVE-2026-66400?

CVE-2026-66400 is a medium-severity authentication bypass vulnerability in getgrav grav, published on 29 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Grav Login Plugin versions before 3.8.13 contain an insufficient session expiration vulnerability in TokenStorage.php where the findTriplet() method fails to properly validate Remember Me token timestamps. Attackers with a captured Remember Me cookie can authenticate indefinitely instead of the configured timeout period, as the expiry check compares an array to a scalar value which always evaluates incorrectly in PHP.

Weakness: CWE-613 (DEPRECATED: Insufficient Session Expiration)

## Which versions are affected by CVE-2026-66400?


## How do I fix CVE-2026-66400?

No fix has been published for CVE-2026-66400 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-66400 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-66400 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-66400 and fix it if it is affected.

What it is: CVE-2026-66400 is a medium-severity authentication bypass vulnerability in getgrav grav, published on 29 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-66400 exists.

Affected product: getgrav grav. 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-2026-66400/ (Markdown: https://insights.sbomify.com/CVE-2026-66400/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-66400
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-66400
- OSV: https://osv.dev/vulnerability/CVE-2026-66400

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-66400/
Summaries are generated and may contain mistakes; the official description above is the record.