How severe is CVE-2020-5403?

CVE-2020-5403 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2020-5403 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (62nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-5403?

CVE-2020-5403 primarily affects Pivotal Reactor Netty. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-5403?

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-2020-5403 published?

CVE-2020-5403 was published on 2020-03-03 and last updated on 2026-06-17.

CVE-2020-5403

CVE-2020-5403 is a high-severity vulnerability in Pivotal Reactor Netty with a CVSS 3.x base score of 7.5. 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-755.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 1% (62nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-755
Affected product: Pivotal Reactor Netty
Published: 2020-03-03
Last modified: 2026-06-17

Description

Reactor Netty HttpServer, versions 0.9.3 and 0.9.4, is exposed to a URISyntaxException that causes the connection to be closed prematurely instead of producing a 400 response.

Frequently asked questions

What is CVE-2020-5403?: Reactor Netty HttpServer, versions 0.9.3 and 0.9.4, is exposed to a URISyntaxException that causes the connection to be closed prematurely instead of producing a 400 response.
How severe is CVE-2020-5403?: CVE-2020-5403 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2020-5403 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (62nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-5403?: CVE-2020-5403 primarily affects Pivotal Reactor Netty. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-5403?: 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-2020-5403 published?: CVE-2020-5403 was published on 2020-03-03 and last updated on 2026-06-17.

References

https://pivotal.io/security/cve-2020-5403

Affected products (2)

cpe:2.3:a:pivotal:reactor_netty:0.9.3:*:*:*:*:*:*:*
cpe:2.3:a:pivotal:reactor_netty:0.9.4:*:*:*:*:*:*:*

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