CVE-2020-10109: In Twisted Web through 19.10.0, there was an HTTP request splitting vulnerability

This week

CRITICAL 9.8REMOTEWATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2020-10109 is a critical-severity flaw (CVSS 9.8) affecting twisted, fedora, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In Twisted Web through 19.10.0, there was an HTTP request splitting vulnerability. When presented with a content-length and a chunked encoding header, the content-length took precedence and the remainder of the request body was interpreted as a pipelined request.

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	3.3% (top 12%)
CISA exploited list	No
Weakness	CWE-444
Published	2020-03-12
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: canonical · debian · fedoraproject · twisted

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

Am I affected?

Timeline

2020-03-12 13:15 UTCPublished CVE record published
2026-06-17 02:47 UTCUpdated Record last modified

twisted twisted UPGRADE

Affected: <= 19.10.0

Fixed in: newer than 19.10.0

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 19.10.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade twisted

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade twisted

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

fedoraproject fedora MITIGATE

Affected: 31 · 32

Fixed in: no fixed release known

Safe to downgrade to: a release before 31

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.

debian debian linux MITIGATE

Affected: 9.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 9.0

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.

canonical ubuntu linux MITIGATE

Affected: 14.04 · 16.04 · 18.04 · 19.10

Fixed in: no fixed release known

Safe to downgrade to: a release before 14.04

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.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Python (pip) · Twisted · FIXED · 20.3.0 · vulnerable: < 20.3.0 · source

pip install --upgrade "Twisted>=20.3.0" pip show Twisted

Fedora ELN · python-discovery · FIXED · 1.9.0-1.eln159 · FEDORA-2026-7a881c0c99 · source

sudo dnf upgrade --advisory=FEDORA-2026-7a881c0c99

Fedora 46 · pipx · FIXED · 1.18.11-1.fc46 · FEDORA-2026-443a765287 · source

sudo dnf upgrade --advisory=FEDORA-2026-443a765287

Debian 12 · twisted · FIXED · 18.9.0-7

sudo apt update && sudo apt install --only-upgrade twisted dpkg --compare-versions "$(dpkg-query -W -f='${Version}' twisted)" ge "18.9.0-7" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · twisted · FIXED · 18.9.0-7

sudo apt update && sudo apt install --only-upgrade twisted dpkg --compare-versions "$(dpkg-query -W -f='${Version}' twisted)" ge "18.9.0-7" && echo PATCHED || echo STILL-VULNERABLE

RHEL 7 · python-twisted-web · FIXED · python-twisted-web-12.1.0-7.el7_8

sudo dnf upgrade --advisory=RHSA-2020:1561 rpm -q python-twisted-web

RHEL 6 · python-twisted-web · NOT AFFECTED

Alpine 3.20 · py3-twisted · FIXED · py3-twisted-20.3.0-r0

apk add --upgrade py3-twisted apk info -v py3-twisted

Alpine 3.21 · py3-twisted · FIXED · py3-twisted-20.3.0-r0

apk add --upgrade py3-twisted apk info -v py3-twisted

Alpine 3.22 · py3-twisted · FIXED · py3-twisted-20.3.0-r0

apk add --upgrade py3-twisted apk info -v py3-twisted

Alpine 3.23 · py3-twisted · FIXED · py3-twisted-20.3.0-r0

apk add --upgrade py3-twisted apk info -v py3-twisted

Amazon Linux 2 · see advisory · FIXED · ALAS2-2020-1428 · source

sudo yum update --advisory=ALAS2-2020-1428

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: know.bishopfox.com/advisories
Write-up: know.bishopfox.com/advisories/twisted-version-19.10.0

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-2020-10109?

twisted: upgrade to newer than 19.10.0; fedora: mitigate or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-10109 being exploited?

CVE-2020-10109 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-2020-10109 affect?

CVE-2020-10109 affects twisted, fedora, debian linux. Severity is critical (CVSS 9.8). In Twisted Web through 19.10.0, there was an HTTP request splitting vulnerability. When presented with a content-length and a chunked encoding header, the content-length took precedence and the remainder of the request body was interpreted

How urgent is CVE-2020-10109?

Priority 71/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Ubuntu vulnerabilities · Debian vulnerabilities

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References

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