PatchTheCVECVE-2018-18688: The Portable Document Format (PDF) specification does not provide any information regarding the concrete proce
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MEDIUM 5.3REMOTEDOWNGRADEDOWNGRADEUPGRADE
CVE-2018-18688 is a medium-severity flaw (CVSS 5.3) affecting master pdf editor, foxit reader, phantompdf. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
The Portable Document Format (PDF) specification does not provide any information regarding the concrete procedure of how to validate signatures. Consequently, an Incremental Saving vulnerability exists in multiple products. When an attacker uses the Incremental Saving feature to add pages or annotations, Body Updates are displayed to the user without any action by the signature-validation logic. This affects Foxit Reader before 9.4 and PhantomPD
Why this priority
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 5.3 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 1.1% (top 33%) |
| CISA exploited list | No |
| Weakness | CWE-347 |
| Published | 2021-01-07 |
| Last modified | 2026-06-17 |
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
code-industry master pdf editor DOWNGRADE
Affected: 5.1.12 · 5.1.68 · 5.1.24
Fixed in: no fixed release known
Safe to downgrade to: a release before 5.1.12
1. Check installed version
apt-cache policy master-pdf-editor || rpm -q master-pdf-editor || master-pdf-editor --version
2. No fixed release: DOWNGRADE to a release before 5.1.12 (Debian / Ubuntu)
apt-cache madison master-pdf-editor
sudo apt install master-pdf-editor=<VERSION_BEFORE_5.1.12>
sudo apt-mark hold master-pdf-editor
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list master-pdf-editor
sudo dnf downgrade master-pdf-editor-<VERSION_BEFORE_5.1.12>
sudo dnf versionlock add master-pdf-editor
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
foxitsoftware foxit reader DOWNGRADE
Affected: 9.4 · 9.1.0 · 9.2.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 9.1.0
1. Check installed version
apt-cache policy foxit-reader || rpm -q foxit-reader || foxit-reader --version
2. No fixed release: DOWNGRADE to a release before 9.1.0 (Debian / Ubuntu)
apt-cache madison foxit-reader
sudo apt install foxit-reader=<VERSION_BEFORE_9.1.0>
sudo apt-mark hold foxit-reader
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list foxit-reader
sudo dnf downgrade foxit-reader-<VERSION_BEFORE_9.1.0>
sudo dnf versionlock add foxit-reader
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
foxitsoftware phantompdf UPGRADE
Affected: >= 9.0 and < 9.4 · 8.3.9
Fixed in: 9.4
Safe to downgrade to: a release before 8.3.9
1. Check installed version
apt-cache policy phantompdf || rpm -q phantompdf || phantompdf --version
2. UPGRADE to 9.4 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade phantompdf
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade phantompdf
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
3. If no update is available yet, DOWNGRADE to a release before 8.3.9 (Debian / Ubuntu)
apt-cache madison phantompdf
sudo apt install phantompdf=<VERSION_BEFORE_8.3.9>
sudo apt-mark hold phantompdf
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list phantompdf
sudo dnf downgrade phantompdf-<VERSION_BEFORE_8.3.9>
sudo dnf versionlock add phantompdf
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
gonitro nitro pro DOWNGRADE
Affected: 11.0.3.173
Fixed in: no fixed release known
Safe to downgrade to: a release before 11.0.3.173
1. Check installed version
apt-cache policy nitro-pro || rpm -q nitro-pro || nitro-pro --version
2. No fixed release: DOWNGRADE to a release before 11.0.3.173 (Debian / Ubuntu)
apt-cache madison nitro-pro
sudo apt install nitro-pro=<VERSION_BEFORE_11.0.3.173>
sudo apt-mark hold nitro-pro
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list nitro-pro
sudo dnf downgrade nitro-pro-<VERSION_BEFORE_11.0.3.173>
sudo dnf versionlock add nitro-pro
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
gonitro nitro reader DOWNGRADE
Affected: 5.5.9.2
Fixed in: no fixed release known
Safe to downgrade to: a release before 5.5.9.2
1. Check installed version
apt-cache policy nitro-reader || rpm -q nitro-reader || nitro-reader --version
2. No fixed release: DOWNGRADE to a release before 5.5.9.2 (Debian / Ubuntu)
apt-cache madison nitro-reader
sudo apt install nitro-reader=<VERSION_BEFORE_5.5.9.2>
sudo apt-mark hold nitro-reader
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list nitro-reader
sudo dnf downgrade nitro-reader-<VERSION_BEFORE_5.5.9.2>
sudo dnf versionlock add nitro-reader
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
iskysoft pdf editor 6 DOWNGRADE
Affected: 6.4.2.3521 · 6.6.2.3315 · 6.7.6.3399
Fixed in: no fixed release known
Safe to downgrade to: a release before 6.4.2.3521
1. Check installed version
apt-cache policy pdf-editor-6 || rpm -q pdf-editor-6 || pdf-editor-6 --version
2. No fixed release: DOWNGRADE to a release before 6.4.2.3521 (Debian / Ubuntu)
apt-cache madison pdf-editor-6
sudo apt install pdf-editor-6=<VERSION_BEFORE_6.4.2.3521>
sudo apt-mark hold pdf-editor-6
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list pdf-editor-6
sudo dnf downgrade pdf-editor-6-<VERSION_BEFORE_6.4.2.3521>
sudo dnf versionlock add pdf-editor-6
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2018-18688?
master pdf editor: downgrade or apply the listed mitigation; foxit reader: downgrade or apply the listed mitigation; phantompdf: upgrade to 9.4. Exact commands for each OS are on this page.
Is CVE-2018-18688 being exploited?
CVE-2018-18688 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2018-18688 affect?
CVE-2018-18688 affects master pdf editor, foxit reader, phantompdf. Severity is medium (CVSS 5.3). The Portable Document Format (PDF) specification does not provide any information regarding the concrete procedure of how to validate signatures. Consequently, an Incremental Saving vulnerability exists in multiple products. When an attacke
How urgent is CVE-2018-18688?
Priority 40/100. Remotely exploitable, no login, no user action