CVE-2021-23803: This affects the package latte/latte before 2.10.6

Q: How do I fix CVE-2021-23803?

latte: upgrade to 2.10.6. Exact commands for each OS are on this page.

Q: Is CVE-2021-23803 being exploited?

CVE-2021-23803 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-23803 affect?

CVE-2021-23803 affects latte. Severity is critical (CVSS 9.8). 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

Q: How urgent is CVE-2021-23803?

Priority 63/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

CRITICAL 9.8REMOTEUPGRADE

CVE-2021-23803 is a critical-severity flaw (CVSS 9.8) affecting latte. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.6% (top 24%)
CISA exploited list	No
Weakness	CWE-863
Published	2021-12-17
Last modified	2026-06-17

Publisher (CNA): Snyk · Vendor: nette

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-12-17 20:15 UTCPublished CVE record published
2026-06-17 03:38 UTCUpdated Record last modified

nette latte UPGRADE

Affected: < 2.10.6

Fixed in: 2.10.6

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy latte || rpm -q latte || latte --version

2. UPGRADE to 2.10.6 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade latte

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade latte

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-23803?

latte: upgrade to 2.10.6. Exact commands for each OS are on this page.

Is CVE-2021-23803 being exploited?

CVE-2021-23803 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-23803 affect?

CVE-2021-23803 affects latte. Severity is critical (CVSS 9.8). 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

How urgent is CVE-2021-23803?

Priority 63/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2022-21648 HIGH 8.2 UPGRADE Latte is an open source template engine for PHP

References

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