CVE-2020-13758: modules/security/classes/general.post_filter.php/post_filter.php in the Web Application Firewall in Bitrix24 t

Q: How do I fix CVE-2020-13758?

bitrix24: upgrade to newer than 20.0.950. Exact commands for each OS are on this page.

Q: Is CVE-2020-13758 being exploited?

CVE-2020-13758 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-2020-13758 affect?

CVE-2020-13758 affects bitrix24. Severity is medium (CVSS 6.1). modules/security/classes/general.post_filter.php/post_filter.php in the Web Application Firewall in Bitrix24 through 20.0.950 allows XSS by placing %00 before the payload.

Q: How urgent is CVE-2020-13758?

Priority 41/100. Public exploit reference

This month

MEDIUM 6.1UPGRADE

CVE-2020-13758 is a medium-severity flaw (CVSS 6.1) affecting bitrix24. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

modules/security/classes/general.post_filter.php/post_filter.php in the Web Application Firewall in Bitrix24 through 20.0.950 allows XSS by placing %00 before the payload.

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.9% (top 42%)
CISA exploited list	No
Weakness	CWE-79
Published	2020-06-01
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: bitrix

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

Am I affected?

Timeline

2020-06-01 19:15 UTCPublished CVE record published
2026-06-17 02:53 UTCUpdated Record last modified

bitrix bitrix24 UPGRADE

Affected: <= 20.0.950

Fixed in: newer than 20.0.950

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy bitrix24 || rpm -q bitrix24 || bitrix24 --version

2. UPGRADE to newer than 20.0.950 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade bitrix24

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade bitrix24

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-2020-13758?

bitrix24: upgrade to newer than 20.0.950. Exact commands for each OS are on this page.

Is CVE-2020-13758 being exploited?

CVE-2020-13758 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-2020-13758 affect?

CVE-2020-13758 affects bitrix24. Severity is medium (CVSS 6.1). modules/security/classes/general.post_filter.php/post_filter.php in the Web Application Firewall in Bitrix24 through 20.0.950 allows XSS by placing %00 before the payload.

How urgent is CVE-2020-13758?

Priority 41/100. Public exploit reference

Software pages

PHP vulnerabilities

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References

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