What is CVE-2021-3818?

CVE-2021-3818 is a medium-severity vulnerability in Getgrav Getgrav/grav, classified under Reliance on Cookies without Validation and Integrity Checking. CVSS score: 5.3/10. Published 2021-09-27.

How severe is CVE-2021-3818?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Is CVE-2021-3818 known to be exploited?

2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Getgrav Getgrav/grav

CVE-2021-3818

grav is vulnerable to Reliance on Cookies without Validation and Integrity Checking

Published 2021-09-27 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.025 (84.1th percentile), scored 2026-10-19.

Low probability of exploitation in the next 30 days, but still tracked. 84th percentile — 84.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.025 · newest: 0.025 · change: 0.000

Affected products

Getgrav Getgrav/grav — versions unspecified
Getgrav Grav

Weakness classification (CWE)

CWE-565 — Reliance on Cookies without Validation and Integrity Checking

Public proof-of-concept exploits

References

huntr.dev/bounties/c2bc65af-7b93-4020-886e-8cdaeb0a58ea (Exploit, Patch, Third Party Advisory)
github.com/getgrav/grav/commit/c51fb1779b83f620c0b6f3548d4a96322b55df07 (Third Party Advisory)

Frequently asked questions

What is CVE-2021-3818?: CVE-2021-3818 is a medium-severity vulnerability in Getgrav Getgrav/grav, classified under Reliance on Cookies without Validation and Integrity Checking. CVSS score: 5.3/10. Published 2021-09-27.
How severe is CVE-2021-3818?: Medium severity. CVSS v3 base score is 5.3 out of 10.
Is CVE-2021-3818 known to be exploited?: 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.