How severe is CVE-2020-17523?

CVE-2020-17523 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-17523 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 86% (100th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-17523?

CVE-2020-17523 affects Apache Shiro. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-17523?

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

When was CVE-2020-17523 published?

CVE-2020-17523 was published on 2021-02-03 and last updated on 2026-06-17.

CVE-2020-17523

CVE-2020-17523 is a critical-severity vulnerability in Apache Shiro with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 86% places it in the 100th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-287.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 9.0
EPSS exploit prediction: 86% (100th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-287
Affected product: Apache Shiro
Published: 2021-02-03
Last modified: 2026-06-17

Description

Apache Shiro before 1.7.1, when using Apache Shiro with Spring, a specially crafted HTTP request may cause an authentication bypass.

Frequently asked questions

What is CVE-2020-17523?: Apache Shiro before 1.7.1, when using Apache Shiro with Spring, a specially crafted HTTP request may cause an authentication bypass.
How severe is CVE-2020-17523?: CVE-2020-17523 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-17523 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 86% (100th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-17523?: CVE-2020-17523 affects Apache Shiro. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-17523?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2020-17523 published?: CVE-2020-17523 was published on 2021-02-03 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:apache:shiro:*:*:*:*:*:*:*:*

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Other CWE-287 (Improper Authentication) vulnerabilities

CVE-2026-45480 — Critical (CVSS 10.0): Improper authentication in Azure Active Directory allows an unauthorized attacker to elevate privileges over a network.
CVE-2026-46389 — Critical (CVSS 10.0): UDS Identity Config builds the Keycloak configuration image (realm, plugins, theme, truststore, JARs) consumed by UDS…
CVE-2026-10611 — Critical (CVSS 10.0): An authentication bypass vulnerability exists in MISP when LDAP mixed authentication is enabled with OTP enforcement.…
CVE-2026-47280 — Critical (CVSS 10.0): Improper authentication in Azure Resource Manager (ARM) allows an unauthorized attacker to elevate privileges over a…
CVE-2026-42822 — Critical (CVSS 10.0): Improper authentication in Azure Local Disconnected Operations allows an unauthorized attacker to elevate privileges…
CVE-2026-20182 — Critical (CVSS 10.0): May 2026: This security advisory provides the details and fix information for a vulnerability that was discovered and…

Browse all CWE-287 (Improper Authentication) vulnerabilities →