Skip to content
Fencer Vulns
low 3.3

CVE-2018-18020 json

In QPDF 8.2.1, in libqpdf/QPDFWriter.cc, QPDFWriter::unparseObject and QPDFWriter::unparseChild have recursive calls for a long time, which…

published 2018-10-06 8 y ago modified 2026-06-17 4 mo ago also EUVD-2018-9759

cvss
3.3
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.2%
EPSS 1.2% chance of exploitation in 30 days, percentile 68%
public exploits
0
none known

Summary

In QPDF 8.2.1, in libqpdf/QPDFWriter.cc, QPDFWriter::unparseObject and QPDFWriter::unparseChild have recursive calls for a long time, which allows remote attackers to cause a denial of service via a crafted PDF file.

Patch / fix

  • qpdf Debian 14, Debian 13, Debian 12 9.0.0-1

debian advisories DEBIAN-CVE-2018-18020

  • qpdf Ubuntu 18.04 LTS 8.0.2-3ubuntu0.1
  • qpdf Ubuntu Pro 16.04 LTS 8.0.2-3~16.04.1+esm1

ubuntu advisories UBUNTU-CVE-2018-18020

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2018-18020 updated cvss 3.3

qpdf: recursive calls can lead to a DoS in libqpdf/QPDFWriter.cc

  • Red Hat Enterprise Linux 8 qpdf, qpdf-libs
    affected: no fix available “Fix deferred”
  • Red Hat Enterprise Linux 7 qpdf, qpdf-libs
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.21% chance of exploitation in the next 30 days, higher than 68% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/qpdf/qpdf/issues/243 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.0 3.3 CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:N/A:P

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.