How severe is CVE-2025-59830?

CVE-2025-59830 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-2025-59830 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-59830?

CVE-2025-59830 affects Rack. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-59830?

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.

Does CVE-2025-59830 have an EU (EUVD) identifier?

Yes. CVE-2025-59830 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-31103.

When was CVE-2025-59830 published?

CVE-2025-59830 was published on 2025-09-25 and last updated on 2026-06-17.

CVE-2025-59830

CVE-2025-59830 is a high-severity vulnerability in Rack 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-400.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 1% (41st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-31103
Weakness: CWE-400
Affected product: Rack
Published: 2025-09-25
Last modified: 2026-06-17

Description

Rack is a modular Ruby web server interface. Prior to version 2.2.18, Rack::QueryParser enforces its params_limit only for parameters separated by &, while still splitting on both & and ;. As a result, attackers could use ; separators to bypass the parameter count limit and submit more parameters than intended. Applications or middleware that directly invoke Rack::QueryParser with its default configuration (no explicit delimiter) could be exposed to increased CPU and memory consumption. This can be abused as a limited denial-of-service vector. This issue has been patched in version 2.2.18.

Frequently asked questions

What is CVE-2025-59830?: Rack is a modular Ruby web server interface. Prior to version 2.2.18, Rack::QueryParser enforces its params_limit only for parameters separated by &, while still splitting on both & and ;. As a result, attackers could use ; separators to bypass the parameter count limit and submit more parameters than intended. Applications or middleware that directly invoke Rack::QueryParser with its default configuration (no explicit delimiter) could be exposed to increased CPU and memory consumption. This can be abused as a limited denial-of-service vector. This issue has been patched in version 2.2.18.
How severe is CVE-2025-59830?: CVE-2025-59830 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-2025-59830 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-59830?: CVE-2025-59830 affects Rack. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-59830?: 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.
Does CVE-2025-59830 have an EU (EUVD) identifier?: Yes. CVE-2025-59830 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-31103.
When was CVE-2025-59830 published?: CVE-2025-59830 was published on 2025-09-25 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*

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