# CVE-2026-91768: IPv6 ACL bypass in FastCGI listen.allowed_clients due to partial address comparison (memcmp 12 bytes)

> Attackers can bypass FastCGI client access controls by exploiting a partial IPv6 address comparison, allowing unauthorized access to endpoints.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Sep 2026
- **Updated:** 28 Sep 2026
- **Also known as:** AZL-104895, BELL-CVE-2026-91768, BIT-libphp-2026-91768, BIT-php-2026-91768, BIT-php-min-2026-91768, CLEANSTART-2026-XM64150, DEBIAN-CVE-2026-91768, ECHO-a027-5d9a-9741, MINI-3rrh-7j3v-gw3f, MINI-4hmg-w75g-7p3j, MINI-9rjj-gw8p-rgfr, MINI-h852-rj78-9667, MINI-mchf-p5j9-8jwj, MINI-qhpp-32m2-634c, MINI-wh53-5qj2-545x, MINI-wvh8-cgg4-rp39, UBUNTU-CVE-2026-91768

## What is CVE-2026-91768?

CVE-2026-91768 is a medium-severity authentication bypass vulnerability in Php Php, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The IPv6 branch of the FastCGI client access check compares only the first 12 bytes of a 16-byte IPv6 address, so listen.allowed_clients matches on a /96 prefix instead of the exact address. An attacker who can source an address sharing the first 96 bits with an allowed one passes the check and reaches the FastCGI endpoint.

Weakness: CWE-1023 (Incomplete Comparison with Missing Factors)

## Which versions are affected by CVE-2026-91768?

3 open source packages ship an affected version, including libphp, php and php-min. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `libphp` | Bitnami | From 8.2.0 | 8.2.34, 8.3.35, 8.4.26, 8.5.11 |
| `php` | Bitnami | From 8.2.0 | 8.2.34, 8.3.35, 8.4.26, 8.5.11 |
| `php-min` | Bitnami | From 8.2.0 | 8.2.34, 8.3.35, 8.4.26, 8.5.11 |

Products: Php Php.

## How do I fix CVE-2026-91768?

Upgrade libphp to a fixed version for your release line: 8.2.34, 8.3.35, 8.4.26 or 8.5.11.

## Is CVE-2026-91768 being exploited?

There is no known exploitation of CVE-2026-91768 in the wild and no public exploit code.

## Other vulnerabilities in Php Php

- [CVE-2012-2688](https://insights.sbomify.com/CVE-2012-2688/): Integer overflow in n/a (critical 10.0)
- [CVE-2012-2376](https://insights.sbomify.com/CVE-2012-2376/): Memory corruption in n/a (critical 10.0)
- [CVE-2011-3268](https://insights.sbomify.com/CVE-2011-3268/): Memory corruption in n/a (critical 10.0)
- [CVE-2009-4143](https://insights.sbomify.com/CVE-2009-4143/): Other in n/a (critical 10.0)
- [CVE-2008-5557](https://insights.sbomify.com/CVE-2008-5557/): Memory corruption in n/a (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-91768 and fix it if it is affected.

What it is: CVE-2026-91768 is a medium-severity authentication bypass vulnerability in Php Php, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-91768 in the wild and no public exploit code.

Affected packages and fixed versions:
- libphp (Bitnami): affected from 8.2.0; fixed in 8.2.34, 8.3.35, 8.4.26, 8.5.11
- php (Bitnami): affected from 8.2.0; fixed in 8.2.34, 8.3.35, 8.4.26, 8.5.11
- php-min (Bitnami): affected from 8.2.0; fixed in 8.2.34, 8.3.35, 8.4.26, 8.5.11

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-2026-91768/ (Markdown: https://insights.sbomify.com/CVE-2026-91768/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-91768
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-91768
- OSV: https://osv.dev/vulnerability/CVE-2026-91768

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-91768/
Summaries are generated and may contain mistakes; the official description above is the record.