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No exploitation reported

CVE-2019-16254

No exploitation reported by the sources we read.

  • Published2019-11-26
  • WeaknessCWE-74

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2019-11-2618:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2019-16254?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2019-16254?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Ruby
BranchAffectedFixed in
2.3≤ 2.3.0no fix published
2.4≥ 2.4.0, ≤ 2.4.7no fix published
2.5≥ 2.5.0, ≤ 2.5.6no fix published
2.6≥ 2.6.0, ≤ 2.6.4no fix published
Debian debian linux
BranchAffectedFixed in
8.0= 8.0no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • rubygem-abrtAlmaLinux:8all versions · fixed in 0.3.0-4.module_el8.5.0+259+8cec6917and 1 other package
  • rubygem-abrtAlmaLinux:8all versions · fixed in 0.3.0-4.module_el8.5.0+2623+08a8ba32and 1 other package
  • rubygem-abrtAlmaLinux:8all versions · fixed in 0.3.0-4.module_el8.5.0+2625+ec418553and 1 other package
  • rubygem-bsonAlmaLinux:8all versions · fixed in 4.3.0-2.module_el8.5.0+259+8cec6917and 1 other package
  • rubygem-bsonAlmaLinux:8all versions · fixed in 4.3.0-2.module_el8.5.0+2625+ec418553and 1 other package
  • rubygem-bsonAlmaLinux:8all versions · fixed in 4.5.0-1.module_el8.5.0+250+ba22dbf7and 1 other package
  • rubygem-bsonAlmaLinux:8all versions · fixed in 4.5.0-1.module_el8.5.0+2623+08a8ba32and 1 other package
  • rubygem-mongoAlmaLinux:8all versions · fixed in 2.5.1-2.module_el8.5.0+259+8cec6917and 1 other package

11 more package ranges on OSV.dev

Full record on NVD

Fix

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • NVDCVSS 3.15.3read 2026-10-23
  • NVDCVSS 2.05read 2026-10-23
  • NVDweakness (CWE)CWE-74read 2026-10-23
  • FIRST EPSSEPSS score4.6 %2026-10-23
  • OSVaffected packages—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Published
2019-11-26
Last Modified
2026-06-17
NVD status
Modified

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.

Is CVE-2019-16254 actively exploited?

Active exploitation of CVE-2019-16254 has not been confirmed. Its EPSS score was 4.6% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2019-16254?

CVE-2019-16254 has a CVSS v3 base score of 5.3 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

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