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Vulnerability details: VCID-apv4-1x4w-kkcg
Vulnerability ID VCID-apv4-1x4w-kkcg
Aliases CVE-2021-35955
GHSA-hr3h-x6gq-rqcp
Summary
Status Published
Exploitability 0.5
Weighted Severity 6.2
Risk 3.1
Affected and Fixed Packages Package Details
Weaknesses (3)
CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
epss 0.00364 https://api.first.org/data/v1/epss?cve=CVE-2021-35955
epss 0.00364 https://api.first.org/data/v1/epss?cve=CVE-2021-35955
cvssv3.1 5.9 https://contao.org/en/news/contao-4-9-16-and-4-11-5-are-available.html
generic_textual MODERATE https://contao.org/en/news/contao-4-9-16-and-4-11-5-are-available.html
cvssv3.1 5.9 https://contao.org/en/security-advisories/cross-site-scripting-via-html-attributes-in-the-back-end.html
generic_textual MODERATE https://contao.org/en/security-advisories/cross-site-scripting-via-html-attributes-in-the-back-end.html
cvssv3.1_qr MODERATE https://github.com/advisories/GHSA-hr3h-x6gq-rqcp
cvssv3.1 5.9 https://github.com/contao/contao
generic_textual MODERATE https://github.com/contao/contao
cvssv3.1 5.9 https://github.com/contao/contao/security/advisories/GHSA-hr3h-x6gq-rqcp
cvssv3.1_qr MODERATE https://github.com/contao/contao/security/advisories/GHSA-hr3h-x6gq-rqcp
generic_textual MODERATE https://github.com/contao/contao/security/advisories/GHSA-hr3h-x6gq-rqcp
cvssv3.1 5.9 https://github.com/FriendsOfPHP/security-advisories/blob/master/contao/contao/CVE-2021-35955.yaml
generic_textual MODERATE https://github.com/FriendsOfPHP/security-advisories/blob/master/contao/contao/CVE-2021-35955.yaml
cvssv3.1 5.9 https://github.com/FriendsOfPHP/security-advisories/blob/master/contao/core-bundle/CVE-2021-35955.yaml
generic_textual MODERATE https://github.com/FriendsOfPHP/security-advisories/blob/master/contao/core-bundle/CVE-2021-35955.yaml
cvssv3.1 5.9 https://nvd.nist.gov/vuln/detail/CVE-2021-35955
generic_textual MODERATE https://nvd.nist.gov/vuln/detail/CVE-2021-35955
Reference id Reference type URL
https://api.first.org/data/v1/epss?cve=CVE-2021-35955
https://contao.org/en/news/contao-4-9-16-and-4-11-5-are-available.html
https://contao.org/en/security-advisories/cross-site-scripting-via-html-attributes-in-the-back-end.html
https://github.com/contao/contao
https://github.com/contao/contao/security/advisories/GHSA-hr3h-x6gq-rqcp
https://github.com/FriendsOfPHP/security-advisories/blob/master/contao/contao/CVE-2021-35955.yaml
https://github.com/FriendsOfPHP/security-advisories/blob/master/contao/core-bundle/CVE-2021-35955.yaml
https://nvd.nist.gov/vuln/detail/CVE-2021-35955
GHSA-hr3h-x6gq-rqcp https://github.com/advisories/GHSA-hr3h-x6gq-rqcp
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L Found at https://contao.org/en/news/contao-4-9-16-and-4-11-5-are-available.html
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L Found at https://contao.org/en/security-advisories/cross-site-scripting-via-html-attributes-in-the-back-end.html
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L Found at https://github.com/contao/contao
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L Found at https://github.com/contao/contao/security/advisories/GHSA-hr3h-x6gq-rqcp
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L Found at https://github.com/FriendsOfPHP/security-advisories/blob/master/contao/contao/CVE-2021-35955.yaml
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L Found at https://github.com/FriendsOfPHP/security-advisories/blob/master/contao/core-bundle/CVE-2021-35955.yaml
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L Found at https://nvd.nist.gov/vuln/detail/CVE-2021-35955
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.58836
EPSS Score 0.00364
Published At June 11, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-06-12T02:01:37.320647+00:00 EPSS Importer Import https://epss.cyentia.com/epss_scores-current.csv.gz 38.6.0