How severe is CVE-2021-23803?

CVE-2021-23803 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-23803 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-23803?

CVE-2021-23803 affects Nette Latte. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-23803?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-23803 published?

CVE-2021-23803 was published on 2021-12-17 and last updated on 2026-06-17.

CVE-2021-23803

CVE-2021-23803 is a critical-severity vulnerability in Nette Latte with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-863.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 2% (73rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-863
Affected product: Nette Latte
Published: 2021-12-17
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2021-23803?: CVE-2021-23803 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-23803 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-23803?: CVE-2021-23803 affects Nette Latte. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-23803?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-23803 published?: CVE-2021-23803 was published on 2021-12-17 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:nette:latte:*:*:*:*:*:*:*:*

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