CVE-2020-36320 | Regular expression Denial of Service (ReDoS) in EmailValidator class in Vaadin 7

Exp

Unsafe validation RegEx in EmailValidator class in com.vaadin:vaadin-server versions 7.0.0 through 7.7.21 (Vaadin 7.0.0 through 7.7.21) allows attackers to cause uncontrolled resource consumption by submitting malicious email addresses.

Published: 2021-04-23 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-36320 is rated High Exploit Risk (73.4/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.96%). 1 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +1.23% over the last day, indicating growing attacker interest. Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2020-36320

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2020-36320

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.72% 1.96% +1.23%
2 2025-12-28 0.56% 0.72% +0.16%
3 2025-12-27 — 0.56% —

Full EPSS history (17 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-36320

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2020-36320

GitHub Security Advisory for CVE-2020-36320

GHSA-42j4-733x-5vcf · Severity: high · Ecosystem: maven — Regular expression denial of service (ReDoS) in EmailValidator class in Vaadin 7

Affected software / configurations for CVE-2020-36320

Vendor Product Version Raw CPE
vaadin vaadin >= 7.0.0, < 7.7.22 cpe:2.3:a:vaadin:vaadin:*:*:*:*:*:*:*:*

References for CVE-2020-36320

URL Tags
https://github.com/vaadin/framework/issues/7757 Exploit Patch Third Party Advisory
https://github.com/vaadin/framework/pull/12104 Patch Third Party Advisory
https://vaadin.com/security/cve-2020-36320 Vendor Advisory
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