What is CVE-2019-16771?

CVE-2019-16771 is a medium-severity vulnerability in Line Armeria, classified under HTTP Response Splitting. CVSS score: 4.8/10. Published 2019-12-06.

How severe is CVE-2019-16771?

Medium severity. CVSS v3 base score is 4.8 out of 10.

Vulnerability in Line Armeria

CVE-2019-16771

Versions of Armeria 0.85.0 through and including 0.96.0 are vulnerable to HTTP response splitting, which allows remote attackers to inject arbitrary HTTP headers via CRLF sequences when unsanitized data is used to populate the headers of an HTTP response. This vulnerability has been patched in 0.97.0. Potential impacts of this vulnerability include cross-user defacement, cache poisoning, Cross-site scripting (XSS), and page hijacking.

Published 2019-12-06 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.010 (60.8th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 61st percentile — 60.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.010 · newest: 0.010 · change: 0.000

Affected products

Line Armeria — versions < 0.97.0
Linecorp Armeria

Weakness classification (CWE)

References

github.com/line/armeria/security/advisories/GHSA-35fr-h7jr-hh86 (Mailing List, Third Party Advisory)
github.com/line/armeria/commit/b597f7a865a527a84ee3d6937075cfbb4470ed20 (Patch, Vendor Advisory)

Frequently asked questions

What is CVE-2019-16771?: CVE-2019-16771 is a medium-severity vulnerability in Line Armeria, classified under HTTP Response Splitting. CVSS score: 4.8/10. Published 2019-12-06.
How severe is CVE-2019-16771?: Medium severity. CVSS v3 base score is 4.8 out of 10.