What is CVE-2019-11555?

CVE-2019-11555 is a medium-severity vulnerability in W1.fi Hostapd, classified under NULL Pointer Dereference. CVSS score: 5.9/10. Published 2019-04-26.

How severe is CVE-2019-11555?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Is CVE-2019-11555 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

NULL pointer dereference in W1.fi Hostapd

CVE-2019-11555

The EAP-pwd implementation in hostapd (EAP server) before 2.8 and wpa_supplicant (EAP peer) before 2.8 does not validate fragmentation reassembly state properly for a case where an unexpected fragment could be received. This could result in process termination due to a NULL pointer dereference (denial of service). This affects eap_server/eap_server_pwd.c and eap_peer/eap_pwd.c.

Published 2019-04-26 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.033 (87.9th percentile), scored 2026-10-01.

Low probability of exploitation in the next 30 days, but still tracked. 88th percentile — 87.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.033 · newest: 0.033 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-476 — NULL Pointer Dereference

Public proof-of-concept exploits

ARPSyndicate/cve-scores

References

www.openwall.com/lists/oss-security/2019/04/18/6 (Patch, Mailing List, Third Party Advisory)
w1.fi/security/2019-5/eap-pwd-message-reassembly-issue-with-unexpected-fragment… (Vendor Advisory)
w1.fi/security/2019-5/ (Patch, Vendor Advisory)
www.openwall.com/lists/oss-security/2019/04/26/1 (mailing-list, Patch, Mailing List, Third Party Advisory)
usn.ubuntu.com/3969-1/ (vendor-advisory)
usn.ubuntu.com/3969-2/ (vendor-advisory)
lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
security.FreeBSD.org/advisories/FreeBSD-SA-19:03.wpa.asc (vendor-advisory)
seclists.org/bugtraq/2019/May/40 (mailing-list)
www.debian.org/security/2019/dsa-4450 (vendor-advisory)

Frequently asked questions

What is CVE-2019-11555?: CVE-2019-11555 is a medium-severity vulnerability in W1.fi Hostapd, classified under NULL Pointer Dereference. CVSS score: 5.9/10. Published 2019-04-26.
How severe is CVE-2019-11555?: Medium severity. CVSS v3 base score is 5.9 out of 10.
Is CVE-2019-11555 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.