CVE-2026-100671

What it is

Grav is a flat-file CMS. In versions 2.0.19 through 2.0.24 — and in 2.0.0 through 2.0.18 and 1.7.x only where content Twig has been explicitly enabled — page content authored by a user holding only page-write permission is rendered through a Twig sandbox that allowlists get_cookie(), which returns any cookie sent with the current request, including the visitor's session cookie. Because the read occurs server-side via filter_input(INPUT_COOKIE, ...), the HttpOnly, Secure and SameSite attributes offer no protection. Grav then stores the finished post-Twig output in a page-content cache keyed only on page identity and the configuration checksum, with no session, user or request dimension and no bypass for authenticated visitors. A page published by a page-write user can therefore capture the session identifier of the next administrator who views it, after which the cached output serves that identifier to unauthenticated visitors, who can replay the cookie to authenticate as that administrator. Since 2.0.19, security.twig_content.process_enabled defaults to true and Security::applyTwigContentDefault() derives each page's process.twig flag from that gate, so content Twig runs on every page with no frontmatter or operator action. Fixed in 2.0.25; 1.7.x is outside the backport scope.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account, but needs a user to act. High risk of data exposure, data tampering, service disruption.

Exploit odds

0.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-09-26 02:34 UTC ReservedThe CVE id was reserved by its CNA
2. 2026-09-26 14:16 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-09-28 19:16 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.4% in the next 30 days (EPSS).
• Severity: 8.6 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-09-26 14:16 UTC

Last modified

2026-09-28 19:16 UTC

Exploit probability

0.4% · EPSS, next 30 days

Weakness

CWE-200 · Information exposure

Record status

Deferred

Attack profile CVSS 4.0 · 8.6

Attack vector

Network

Complexity

Low

Attack requirements

None

Privileges needed

Low

User interaction

Passive

Confidentiality

High

Integrity

High

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-100671.md and follow it. Check whether this project is affected by CVE-2026-100671. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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