What is CVE-2018-18661?

CVE-2018-18661 is a medium-severity vulnerability in Libtiff, classified under NULL Pointer Dereference. CVSS score: 6.5/10. Published 2018-10-26.

How severe is CVE-2018-18661?

Medium severity. CVSS v3 base score is 6.5 out of 10.

NULL pointer dereference in Libtiff

CVE-2018-18661

An issue was discovered in LibTIFF 4.0.9. There is a NULL pointer dereference in the function LZWDecode in the file tif_lzw.c.

Published 2018-10-26 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.029 (86.3th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 86th percentile — 86.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.029 · newest: 0.029 · change: 0.000

Affected products

Libtiff — versions 4.0.9
Canonical Ubuntu Linux — versions 14.04, 16.04, 18.04

Weakness classification (CWE)

CWE-476 — NULL Pointer Dereference

References

usn.ubuntu.com/3864-1/ (vendor-advisory, Third Party Advisory)
bugzilla.maptools.org/show_bug.cgi (Exploit, Patch, Third Party Advisory, Issue Tracking)
www.securityfocus.com/bid/105762 (VDB Entry, Third Party Advisory, vdb-entry)
access.redhat.com/errata/RHSA-2019:2053 (vendor-advisory)
lists.debian.org/debian-lts-announce/2019/11/msg00027.html (mailing-list)

Frequently asked questions

What is CVE-2018-18661?: CVE-2018-18661 is a medium-severity vulnerability in Libtiff, classified under NULL Pointer Dereference. CVSS score: 6.5/10. Published 2018-10-26.
How severe is CVE-2018-18661?: Medium severity. CVSS v3 base score is 6.5 out of 10.