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Vulnerability details: VCID-c626-g36k-3ka3
Vulnerability ID VCID-c626-g36k-3ka3
Aliases CVE-2021-20185
GHSA-c3j6-33r4-89q3
Summary Moodle Client side denial of service via personal message It was found in Moodle before version 3.10.1, 3.9.4, 3.8.7 and 3.5.16 that messaging did not impose a character limit when sending messages, which could result in client-side (browser) denial of service for users receiving very large messages.
Status Published
Exploitability 0.5
Weighted Severity 6.2
Risk 3.1
Affected and Fixed Packages Package Details
Weaknesses (4)
CWE-400 Uncontrolled Resource Consumption
CWE-770 Allocation of Resources Without Limits or Throttling
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
epss 0.00481 https://api.first.org/data/v1/epss?cve=CVE-2021-20185
epss 0.00481 https://api.first.org/data/v1/epss?cve=CVE-2021-20185
cvssv3.1_qr MODERATE https://github.com/advisories/GHSA-c3j6-33r4-89q3
cvssv3.1 5.3 https://github.com/moodle/moodle
generic_textual MODERATE https://github.com/moodle/moodle
cvssv3.1 5.3 https://moodle.org/mod/forum/discuss.php?d=417168
generic_textual MODERATE https://moodle.org/mod/forum/discuss.php?d=417168
cvssv2 5.0 https://nvd.nist.gov/vuln/detail/CVE-2021-20185
cvssv3.1 5.3 https://nvd.nist.gov/vuln/detail/CVE-2021-20185
generic_textual MODERATE https://nvd.nist.gov/vuln/detail/CVE-2021-20185
Reference id Reference type URL
https://api.first.org/data/v1/epss?cve=CVE-2021-20185
https://github.com/moodle/moodle
https://moodle.org/mod/forum/discuss.php?d=417168
https://nvd.nist.gov/vuln/detail/CVE-2021-20185
cpe:2.3:a:moodle:moodle:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:moodle:moodle:*:*:*:*:*:*:*:*
cpe:2.3:a:moodle:moodle:3.10.0:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:moodle:moodle:3.10.0:*:*:*:*:*:*:*
GHSA-c3j6-33r4-89q3 https://github.com/advisories/GHSA-c3j6-33r4-89q3
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Found at https://github.com/moodle/moodle
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:N/UI:N/S:U/C:N/I:N/A:L Found at https://moodle.org/mod/forum/discuss.php?d=417168
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: AV:N/AC:L/Au:N/C:N/I:N/A:P Found at https://nvd.nist.gov/vuln/detail/CVE-2021-20185
Exploitability (E) Access Vector (AV) Access Complexity (AC) Authentication (Au) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

high

functional

unproven

proof_of_concept

not_defined

local

adjacent_network

network

high

medium

low

multiple

single

none

none

partial

complete

none

partial

complete

none

partial

complete
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Found at https://nvd.nist.gov/vuln/detail/CVE-2021-20185
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 0.64141
EPSS Score 0.00481
Published At June 30, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2025-07-01T12:29:18.950237+00:00 GithubOSV Importer Import https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2022/05/GHSA-c3j6-33r4-89q3/GHSA-c3j6-33r4-89q3.json 36.1.3