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NVD / CVE Program· CNA VulnCheck

CVE-2026-100671: Grav before 2.0.25 Session Cookie Theft via Twig Sandbox

Noroxi assessment

Priority: Monitor (action score 34/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.36% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No special conditions are required; it is repeatable.
  • Fixed version: getgrav grav 2.0.25.

Low priority for now. Upgrade to getgrav grav 2.0.25 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 8.6 · v4.0—Proof of concept Fix available
Published
Sep 26, 2026
Updated
Sep 28, 2026
EPSS
0.3% · 30th percentile

Report tools

JSON

Action score

34

Monitor

Low priority for now.

CVSS
34 / 40 · 8.6 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · VulnCheck
8.6
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-100671

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (VulnCheck). Independent of NVD's CPE analysis and usually ahead of it.

  • getgrav grav

    • 2.0.25not affected
    • before 2.0.25affected · semver

Same product

getgrav: all records

Other highest-scoring records for the same primary product.

  • CVE-2025-50286A Remote Code Execution (RCE) vulnerability in Grav CMS v1.7.48 allows an authenticated admin to upload a malicious plugin via the /admin/to
    60This week
  • CVE-2024-27921Grav File Upload Path Traversal vulnerability
    53Plan
  • CVE-2025-66301Grav ihas Broken Access Control which allows an Editor to modify the page's YAML Frontmatter to alter form processing actions
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-100669Sep 26, 2026 · Grav before 2.0.25 Sensitive File Disclosure via Case-Variation Bypass
    34Monitor
  • ← EarlierCVE-2026-100670Sep 26, 2026 · Grav CMS 2.0.14 through 2.0.24 Privilege Escalation via Blueprint Guard Bypass
    34Monitor
  • Later →CVE-2026-109315Oct 12, 2026 · Grav 2.0.22 before 2.1.7 Clockwork Debugger Token Disclosure via Twig Sandbox
    28Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
getgrav grav2.0.25Vendor (CNA)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:02026-10-01

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. First PoC+4 d
  3. TodayNov 3, 2026+38 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-929169 days apartGrav through 2.0.21 Unauthenticated Information Disclosure via Clockwork
    34Monitor
  • CVE-2026-929179 days apartGrav 2.0.0-rc.1 through 2.0.21 Configuration Disclosure via print_r
    34Monitor
  • CVE-2026-10932516 days apartGrav from 2.0.22 before 2.1.7 Clockwork Profiler Authentication Bypass via Proxy
    34Monitor
  • CVE-2026-11278123 days apartGrav 2.0.0 before 2.2.2 Information Disclosure via Form config-*@ Directives
    34Monitor
  • CVE-2026-11760431 days apartGrav from 1.7.53.3 before 1.7.53.6 Clockwork Profiler Authorization Bypass via Loopback Fallback
    34Monitor
  • CVE-2026-6145477 days apartGrav before 2.0.4 Information Disclosure via __GRAV_CONFIG__
    34Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
P
Scope
X

Weakness class (CWE)

CWE-200 · Exposure of Sensitive Information to an Unauthorized Actor

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Root cause

The extension requests broader permissions than its function needs and sends the data it collects out for purposes beyond its stated function.

The bug in code

The whole CWE-200 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

json
{  "permissions": ["tabs", "<all_urls>"],  "background": { "service_worker": "analytics.js" }}

Fixed

json
{  "permissions": ["activeTab"],  "host_permissions": ["https://yildiz.example/*"]}

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Exploit maturitynone → poc
  2. Fix✗ → ✓
  3. SSVC exploitation— → poc

For records you follow, these changes also arrive as notifications. →

References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records