How severe is CVE-2019-16254?

CVE-2019-16254 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2019-16254 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (90th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-16254?

CVE-2019-16254 primarily affects Ruby-lang Ruby. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2019-16254?

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

When was CVE-2019-16254 published?

CVE-2019-16254 was published on 2019-11-26 and last updated on 2026-06-17.

CVE-2019-16254

CVE-2019-16254 is a medium-severity vulnerability in Ruby-lang Ruby with a CVSS 3.x base score of 5.3. 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-74.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 5.0
EPSS exploit prediction: 5% (90th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-74
Affected product: Ruby-lang Ruby
Published: 2019-11-26
Last modified: 2026-06-17

Description

Ruby through 2.4.7, 2.5.x through 2.5.6, and 2.6.x through 2.6.4 allows HTTP Response Splitting. If a program using WEBrick inserts untrusted input into the response header, an attacker can exploit it to insert a newline character to split a header, and inject malicious content to deceive clients. NOTE: this issue exists because of an incomplete fix for CVE-2017-17742, which addressed the CRLF vector, but did not address an isolated CR or an isolated LF.

Frequently asked questions

What is CVE-2019-16254?: Ruby through 2.4.7, 2.5.x through 2.5.6, and 2.6.x through 2.6.4 allows HTTP Response Splitting. If a program using WEBrick inserts untrusted input into the response header, an attacker can exploit it to insert a newline character to split a header, and inject malicious content to deceive clients. NOTE: this issue exists because of an incomplete fix for CVE-2017-17742, which addressed the CRLF vector, but did not address an isolated CR or an isolated LF.
How severe is CVE-2019-16254?: CVE-2019-16254 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2019-16254 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (90th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-16254?: CVE-2019-16254 primarily affects Ruby-lang Ruby. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-16254?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2019-16254 published?: CVE-2019-16254 was published on 2019-11-26 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:ruby-lang:ruby:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*

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