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MEDIUM severity

CVE-2021-3818 — grav

MEDIUMFix: getgrav/grav@c51fb17

CVE-2021-3818 is a medium-severity (CVSS 5.3) CWE-565 vulnerability in getgrav/grav. 1 public exploit reference exists, so weaponization risk is real. A fix is available for getgrav/grav — see the affected versions and patch details below.

Reliance on Cookies without Validation and Integrity Checking in getgrav/grav

Also known asGHSA-cg3q-59w7-rvc2
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
1 known
Exploitation data as of Oct 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
2.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs84th percentile — riskier than 84% of all scored CVEsHighest risk
0.00%1.03%2.07%3.10%0.3%2.5%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-3818 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 384,189 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🐘getgrav/grav

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

grav is vulnerable to Reliance on Cookies without Validation and Integrity Checking. A cookie with an overly broad path can be accessed through other applications on the same domain. Since cookies often carry sensitive information such as session identifiers, sharing cookies across applications can lead a vulnerability in one application to cause a compromise in another.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐘Packagistgetgrav/gravall versions1.7.21composer require getgrav/grav:^1.7.21

Affected Products

1 product · 1 configurations
Application
gravgetgrav
< 1.7.22
range
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

grav is vulnerable to Reliance on Cookies without Validation and Integri…

huntr.devNVDSep 2021

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for getgrav/grav, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update getgrav/grav to 1.7.21 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-3818 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

grav is vulnerable to Reliance on Cookies without Validation and Integrity Checking. A cookie with an overly broad path can be accessed through other applications on the same domain. Since cookies often carry sensitive information such as session identifiers, sharing cookies across applications can lead a vulnerability in one application to cause a compromise in another.
O3 Security · Impact-Aware SCA

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CVE-2021-3818: grav — Fixed in 1.7.21