What is CVE-2019-16239?

CVE-2019-16239 is a critical-severity vulnerability in Infradead Openconnect, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.8/10. Published 2019-09-17.

How severe is CVE-2019-16239?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Buffer overflow in Infradead Openconnect

CVE-2019-16239

process_http_response in OpenConnect before 8.05 has a Buffer Overflow when a malicious server uses HTTP chunked encoding with crafted chunk sizes.

Vulnerability class: Buffer Overflow

Published 2019-09-17 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.034 (88.6th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 89th percentile — 88.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.034 · newest: 0.034 · change: 0.000

Affected products

Infradead Openconnect
Canonical Ubuntu Linux — versions 18.04
Debian Linux — versions 8.0, 9.0, 10.0
Fedoraproject Fedora — versions 29, 30, 31
openSUSE Leap — versions 15.0, 15.1

Weakness classification (CWE)

CWE-120 — Buffer Copy without Checking Size of Input (Classic Buffer Overflow)

References

t2.fi/schedule/2019/ (Not Applicable)
lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
lists.infradead.org/pipermail/openconnect-devel/2019-September/005412.html (Broken Link)
lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
lists.debian.org/debian-lts-announce/2019/10/msg00003.html (mailing-list, Mailing List, Third Party Advisory)
lists.opensuse.org/opensuse-security-announce/2019-10/msg00060.html (vendor-advisory, Mailing List, Third Party Advisory)
lists.opensuse.org/opensuse-security-announce/2019-10/msg00061.html (vendor-advisory, Mailing List, Third Party Advisory)
www.debian.org/security/2020/dsa-4607 (vendor-advisory, Third Party Advisory)
seclists.org/bugtraq/2020/Jan/31 (mailing-list, Mailing List, Third Party Advisory)

Frequently asked questions

What is CVE-2019-16239?: CVE-2019-16239 is a critical-severity vulnerability in Infradead Openconnect, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.8/10. Published 2019-09-17.
How severe is CVE-2019-16239?: Critical severity. CVSS v3 base score is 9.8 out of 10.