What is CVE-2021-23803?

CVE-2021-23803 is a critical-severity vulnerability in Nette Latte, classified under Incorrect Authorization. CVSS score: 9.8/10. Published 2021-12-17.

How severe is CVE-2021-23803?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Auth bypass in Nette Latte

CVE-2021-23803

This affects the package latte/latte before 2.10.6. There is a way to bypass allowFunctions that will affect the security of the application. When the template is set to allow/disallow the use of certain functions, adding control characters (x00-x08) after the function will bypass these restrictions.

Vulnerability class: Broken Access Control

Published 2021-12-17 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.016 (74.5th percentile), scored 2026-10-01.

Low probability of exploitation in the next 30 days, but still tracked. 75th percentile — 74.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.016 · newest: 0.016 · change: 0.000

Affected products

Nette Latte
Latte/latte — versions unspecified

Weakness classification (CWE)

CWE-863 — Incorrect Authorization

References

snyk.io/vuln/SNYK-PHP-LATTELATTE-1932226 (Exploit, Patch, Third Party Advisory)
github.com/nette/latte/issues/279 (Exploit, Patch, Third Party Advisory, Issue Tracking)
github.com/nette/latte/commit/227c86eda9a8a6d060ea8501923e768b6d992210 (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-23803?: CVE-2021-23803 is a critical-severity vulnerability in Nette Latte, classified under Incorrect Authorization. CVSS score: 9.8/10. Published 2021-12-17.
How severe is CVE-2021-23803?: Critical severity. CVSS v3 base score is 9.8 out of 10.