CVE-2020-9273: In ProFTPD 1.3.7, it is possible to corrupt the memory pool by interrupting the data transfer channel

This week

HIGH 8.8WATCHLISTDOWNGRADEMITIGATEMITIGATE

CVE-2020-9273 is a high-severity flaw (CVSS 8.8) affecting proftpd, debian linux, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In ProFTPD 1.3.7, it is possible to corrupt the memory pool by interrupting the data transfer channel. This triggers a use-after-free in alloc_pool in pool.c, and possible remote code execution.

Why this priority

High severity
EPSS top 4%: very likely to be exploited
On your watchlist

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

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	11.8% (top 4%)
CISA exploited list	No
Weakness	CWE-416
Published	2020-02-20
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian · fedoraproject · opensuse · proftpd · siemens

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

Am I affected?

Timeline

2020-02-20 16:15 UTCPublished CVE record published
2026-06-17 03:27 UTCUpdated Record last modified

proftpd proftpd DOWNGRADE

Affected: 1.3.7

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.3.7

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 1.3.7 (Debian / Ubuntu)

apt-cache madison proftpd sudo apt install proftpd=<VERSION_BEFORE_1.3.7> sudo apt-mark hold proftpd

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

dnf --showduplicates list proftpd sudo dnf downgrade proftpd-<VERSION_BEFORE_1.3.7> sudo dnf versionlock add proftpd

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.

debian debian linux MITIGATE

Affected: 8.0 · 9.0 · 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

fedoraproject fedora MITIGATE

Affected: 30 · 31

Fixed in: no fixed release known

Safe to downgrade to: a release before 30

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

opensuse backports sle DOWNGRADE

Affected: 15.0 · 15.0 sp1

Fixed in: no fixed release known

Safe to downgrade to: a release before 15.0

1. Check installed version

apt-cache policy backports-sle || rpm -q backports-sle || backports-sle --version

2. No fixed release: DOWNGRADE to a release before 15.0 (Debian / Ubuntu)

apt-cache madison backports-sle sudo apt install backports-sle=<VERSION_BEFORE_15.0> sudo apt-mark hold backports-sle

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

dnf --showduplicates list backports-sle sudo dnf downgrade backports-sle-<VERSION_BEFORE_15.0> sudo dnf versionlock add backports-sle

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.

opensuse leap MITIGATE

Affected: 15.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 15.1

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

siemens simatic net cp 1545-1 firmware MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2020-9273?

proftpd: downgrade or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-9273 being exploited?

CVE-2020-9273 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-2020-9273 affect?

CVE-2020-9273 affects proftpd, debian linux, fedora. Severity is high (CVSS 8.8). In ProFTPD 1.3.7, it is possible to corrupt the memory pool by interrupting the data transfer channel. This triggers a use-after-free in alloc_pool in pool.c, and possible remote code execution.

How urgent is CVE-2020-9273?

Priority 60/100. High severity; EPSS top 4%: very likely to be exploited; On your watchlist

Software pages

Debian vulnerabilities · ProFTPD vulnerabilities · Siemens vulnerabilities

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References

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