# CVE-2026-40080: Cacti: Open Redirect via HTTP_REFERER substring check in auth_login_redirect

> Attackers can redirect users to malicious sites after login if referer-based redirection is enabled, bypassing URL validation.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 25 Jun 2026
- **Updated:** 26 Jun 2026
- **Also known as:** DEBIAN-CVE-2026-40080, GHSA-6gr7-53g8-vchq, UBUNTU-CVE-2026-40080

## What is CVE-2026-40080?

CVE-2026-40080 is a medium-severity vulnerability in Cacti Cacti, published on 25 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Cacti is an open source performance and fault management framework. Versions 1.2.30 and prior are vulnerable to Open Redirect through a substring check rather than a host check at str_contains($referer, CACTI_PATH_URL). When the user's login_opts == '1' (redirect to referer after login), the function used $_SERVER['HTTP_REFERER'] directly.  An attacker could craft a referer such as https://evil.com/cacti/. Where CACTI_PATH_URL is /cacti/, the substring matches and the user is redirected to evil.com after login. The pre-existing validate_redirect_url() helper at lib/html_utility.php performed proper validation but was not invoked from auth_login_redirect(). This issue has been fixed in version 1.2.31.

Weakness: CWE-601 (URL Redirection to Untrusted Site)

## Which versions are affected by CVE-2026-40080?

It affects 1 product.


Products: Cacti Cacti.

## How do I fix CVE-2026-40080?

Upgrade to a fixed version.

## Is CVE-2026-40080 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-40080 exists.

## Other vulnerabilities in Cacti Cacti

- [CVE-2022-46169](https://insights.sbomify.com/CVE-2022-46169/): Cacti Command Injection (critical 9.8, exploited in the wild)
- [CVE-2026-39893](https://insights.sbomify.com/CVE-2026-39893/): Cacti: Pre-authentication SQL injection via rfilter RLIKE clause in graph_view.php (critical 9.8)
- [CVE-2026-39938](https://insights.sbomify.com/CVE-2026-39938/): Cacti: Unauthenticated RCE on Graph Image (critical 9.8)
- [CVE-2026-39955](https://insights.sbomify.com/CVE-2026-39955/): Cacti has Pre-Authentication SQL Injection via unanchored FILTER_VALIDATE_REGEXP in graph_view.php (critical 9.8)
- [CVE-2023-39361](https://insights.sbomify.com/CVE-2023-39361/): Unauthenticated SQL Injection in graph_view.php in Cacti (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40080 and fix it if it is affected.

What it is: CVE-2026-40080 is a medium-severity vulnerability in Cacti Cacti, published on 25 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-40080 exists.

Affected product: Cacti Cacti. 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-2026-40080/ (Markdown: https://insights.sbomify.com/CVE-2026-40080/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40080
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40080
- OSV: https://osv.dev/vulnerability/CVE-2026-40080

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40080/
Summaries are generated and may contain mistakes; the official description above is the record.