How severe is CVE-2020-1757?

CVE-2020-1757 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2020-1757 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-1757?

CVE-2020-1757 primarily affects Redhat Undertow. In total, 12 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-1757?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2020-1757 published?

CVE-2020-1757 was published on 2020-04-21 and last updated on 2026-06-17.

CVE-2020-1757

CVE-2020-1757 is a high-severity vulnerability in Redhat Undertow with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v2: 5.5
EPSS exploit prediction: 2% (72nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Redhat Undertow
Published: 2020-04-21
Last modified: 2026-06-17

Description

A flaw was found in all undertow-2.x.x SP1 versions prior to undertow-2.0.30.SP1, all undertow-1.x.x and undertow-2.x.x versions prior to undertow-2.1.0.Final, where the Servlet container causes servletPath to normalize incorrectly by truncating the path after semicolon which may lead to an application mapping resulting in the security bypass.

Frequently asked questions

What is CVE-2020-1757?: A flaw was found in all undertow-2.x.x SP1 versions prior to undertow-2.0.30.SP1, all undertow-1.x.x and undertow-2.x.x versions prior to undertow-2.1.0.Final, where the Servlet container causes servletPath to normalize incorrectly by truncating the path after semicolon which may lead to an application mapping resulting in the security bypass.
How severe is CVE-2020-1757?: CVE-2020-1757 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2020-1757 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-1757?: CVE-2020-1757 primarily affects Redhat Undertow. In total, 12 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-1757?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2020-1757 published?: CVE-2020-1757 was published on 2020-04-21 and last updated on 2026-06-17.

References

https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2020-1757

Affected products (12)

cpe:2.3:a:redhat:undertow:*:*:*:*:*:*:*:*
cpe:2.3:a:redhat:undertow:2.0.0:sp1:*:*:*:*:*:*
cpe:2.3:a:redhat:undertow:2.0.25:sp1:*:*:*:*:*:*
cpe:2.3:a:redhat:undertow:2.0.26:sp3:*:*:*:*:*:*
cpe:2.3:a:redhat:undertow:2.0.28:sp1:*:*:*:*:*:*
cpe:2.3:a:redhat:undertow:2.0.28:sp2:*:*:*:*:*:*
cpe:2.3:a:redhat:jboss_data_grid:7.0.0:*:*:*:*:*:*:*
cpe:2.3:a:redhat:jboss_enterprise_application_platform:7.0.0:*:*:*:*:*:*:*
cpe:2.3:a:redhat:jboss_fuse:6.0.0:*:*:*:*:*:*:*
cpe:2.3:a:redhat:jboss_fuse:7.0.0:*:*:*:*:*:*:*
cpe:2.3:a:redhat:openshift_application_runtimes:-:*:*:*:*:*:*:*
cpe:2.3:a:redhat:single_sign-on:7.0:*:*:*:*:*:*:*

More vulnerabilities in Redhat Undertow

CVE-2019-10212 — Critical (CVSS 9.8): A flaw was found in, all under 2.0.20, in the Undertow DEBUG log for io.undertow.request.security. If enabled, an…
CVE-2019-3888 — Critical (CVSS 9.8): A vulnerability was found in Undertow web server before 2.0.21. An information exposure of plain text credentials…
CVE-2025-12543 — Critical (CVSS 9.6): A flaw was found in the Undertow HTTP server core, which is used in WildFly, JBoss EAP, and other Java applications.…
CVE-2026-28369 — High (CVSS 8.7): A flaw was found in Undertow. When Undertow receives an HTTP request where the first header line starts with one or…
CVE-2026-28368 — High (CVSS 8.7): A flaw was found in Undertow. This vulnerability allows a remote attacker to construct specially crafted requests where…
CVE-2026-28367 — High (CVSS 8.7): A flaw was found in Undertow. A remote attacker can exploit this vulnerability by sending `\r\r\r` as a header block…

All CVEs affecting Redhat Undertow →

Other CWE-20 (Improper Input Validation) vulnerabilities

CVE-2026-48316 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Improper Input Validation vulnerability that could…
CVE-2026-48281 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Improper Input Validation vulnerability that could…
CVE-2026-48277 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Improper Input Validation vulnerability that could…
CVE-2026-48055 — Critical (CVSS 10.0): Streambert is a cross-platform Electron Desktop App to stream and download any video media. In versions 2.4.0 and…
CVE-2026-34910 — Critical (CVSS 10.0): A malicious actor with access to the network could exploit an Improper Input Validation vulnerability found in UniFi OS…
CVE-2026-33587 — Critical (CVSS 10.0): Lack of user input sanitisation in Open Notebook v1.8.3 allows the application user to execute Python code (and…

Browse all CWE-20 (Improper Input Validation) vulnerabilities →