How severe is CVE-2025-6442?

CVE-2025-6442 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2025-6442 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (34th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-6442?

CVE-2025-6442 affects Ruby-lang Webrick. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-6442?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2025-6442 have an EU (EUVD) identifier?

Yes. CVE-2025-6442 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-19113.

When was CVE-2025-6442 published?

CVE-2025-6442 was published on 2025-06-25 and last updated on 2026-06-17.

CVE-2025-6442

CVE-2025-6442 is a medium-severity vulnerability in Ruby-lang Webrick with a CVSS 3.x base score of 5.9. 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-444.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
EPSS exploit prediction: 0% (34th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-19113
Weakness: CWE-444
Affected product: Ruby-lang Webrick
Published: 2025-06-25
Last modified: 2026-06-17

Description

Ruby WEBrick read_header HTTP Request Smuggling Vulnerability. This vulnerability allows remote attackers to smuggle arbitrary HTTP requests on affected installations of Ruby WEBrick. This issue is exploitable when the product is deployed behind an HTTP proxy that fulfills specific conditions. The specific flaw exists within the read_headers method. The issue results from the inconsistent parsing of terminators of HTTP headers. An attacker can leverage this vulnerability to smuggle arbitrary HTTP requests. Was ZDI-CAN-21876.

Frequently asked questions

What is CVE-2025-6442?: Ruby WEBrick read_header HTTP Request Smuggling Vulnerability. This vulnerability allows remote attackers to smuggle arbitrary HTTP requests on affected installations of Ruby WEBrick. This issue is exploitable when the product is deployed behind an HTTP proxy that fulfills specific conditions. The specific flaw exists within the read_headers method. The issue results from the inconsistent parsing of terminators of HTTP headers. An attacker can leverage this vulnerability to smuggle arbitrary HTTP requests. Was ZDI-CAN-21876.
How severe is CVE-2025-6442?: CVE-2025-6442 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2025-6442 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (34th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-6442?: CVE-2025-6442 affects Ruby-lang Webrick. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-6442?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-6442 have an EU (EUVD) identifier?: Yes. CVE-2025-6442 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-19113.
When was CVE-2025-6442 published?: CVE-2025-6442 was published on 2025-06-25 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:ruby-lang:webrick:*:*:*:*:*:ruby:*:*

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