CVE-2020-5553: mailform version 1.04 allows remote attackers to execute arbitrary PHP code via unspecified vectors.

This week

CRITICAL 9.8REMOTEDOWNGRADE

CVE-2020-5553 is a critical-severity flaw (CVSS 9.8) affecting mailform. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

mailform version 1.04 allows remote attackers to execute arbitrary PHP code via unspecified vectors.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.3% (top 17%)
CISA exploited list	No
Weakness	CWE-94
Published	2020-03-25
Last modified	2026-06-17

Publisher (CNA): JPCERT/CC · Vendor: mailform

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-03-25 02:15 UTCPublished CVE record published
2026-06-17 03:21 UTCUpdated Record last modified

mailform mailform DOWNGRADE

Affected: 1.04

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.04

1. Check installed version

apt-cache policy mailform || rpm -q mailform || mailform --version

2. No fixed release: DOWNGRADE to a release before 1.04 (Debian / Ubuntu)

apt-cache madison mailform sudo apt install mailform=<VERSION_BEFORE_1.04> sudo apt-mark hold mailform

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list mailform sudo dnf downgrade mailform-<VERSION_BEFORE_1.04> sudo dnf versionlock add mailform

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.

Quick answers

How do I fix CVE-2020-5553?

mailform: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-5553 being exploited?

CVE-2020-5553 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-2020-5553 affect?

CVE-2020-5553 affects mailform. Severity is critical (CVSS 9.8). mailform version 1.04 allows remote attackers to execute arbitrary PHP code via unspecified vectors.

How urgent is CVE-2020-5553?

Priority 60/100. Critical severity; Remotely exploitable, no login, no user action

Software pages

PHP vulnerabilities

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References

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