CVE-2019-9948: urllib in Python 2.x through 2.7.16 supports the local_file: scheme, which makes it easier for remote attacker

This week

CRITICAL 9.1REMOTEWATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2019-9948 is a critical-severity flaw (CVSS 9.1) affecting python, leap, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

urllib in Python 2.x through 2.7.16 supports the local_file: scheme, which makes it easier for remote attackers to bypass protection mechanisms that blacklist file: URIs, as demonstrated by triggering a urllib.urlopen('local_file:///etc/passwd') call.

Why this priority

Critical severity
EPSS top 4%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.1 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	11.8% (top 4%)
CISA exploited list	No
Weakness	CWE-22
Published	2019-03-23
Last modified	2026-10-14

Publisher (CNA): MITRE · Vendor: canonical · debian · fedoraproject · opensuse · python · redhat

Last updated 2026-10-14 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2019-03-23 18:29 UTCPublished CVE record published
2026-10-14 07:16 UTCUpdated Record last modified

python python UPGRADE

Affected: >= 2.0 and < 2.7.17 · >= 3.5.0 and < 3.5.8 · >= 3.6.0 and < 3.6.9 · >= 3.7.0 and < 3.7.4

Fixed in: 2.7.17, 3.5.8, 3.6.9, 3.7.4

Safe to downgrade to: a release before 2.0

1. Check installed version

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

2. UPGRADE to 2.7.17 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade python

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 2.0 (Debian / Ubuntu)

apt-cache madison python sudo apt install python=<VERSION_BEFORE_2.0> sudo apt-mark hold python

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list python sudo dnf downgrade python-<VERSION_BEFORE_2.0> sudo dnf versionlock add python

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: 15.0 · 42.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 15.0

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.

debian debian linux MITIGATE

Affected: 8.0 · 9.0

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: 29 · 30

Fixed in: no fixed release known

Safe to downgrade to: a release before 29

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: 12.04 · 14.04 · 16.04 · 18.04 · 19.04

Fixed in: no fixed release known

Safe to downgrade to: a release before 12.04

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.

redhat enterprise linux desktop MITIGATE

Affected: 7.0 · 8.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.0

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.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora 46 · nodejs-pnpm12 · FIXED · 12.17.0-1.fc46 · FEDORA-2026-7adfb2bcdd · source

sudo dnf upgrade --advisory=FEDORA-2026-7adfb2bcdd

Fedora ELN · wget2 · FIXED · 2.3.0-3.eln159 · FEDORA-2026-811b4922a5 · source

sudo dnf upgrade --advisory=FEDORA-2026-811b4922a5

Ubuntu 20.04 · python2.7 · NOT AFFECTED

Ubuntu 22.04 · python2.7 · NOT AFFECTED

RHEL 7 · python · FIXED · python-2.7.5-86.el7

sudo dnf upgrade --advisory=RHSA-2019:2030 rpm -q python

RHEL 7.4 Advanced Update Support · python · FIXED · python-2.7.5-63.el7_4

sudo dnf upgrade --advisory=RHSA-2020:1346 rpm -q python

RHEL 7.4 Telco Extended Update Support · python · FIXED · python-2.7.5-63.el7_4

sudo dnf upgrade --advisory=RHSA-2020:1346 rpm -q python

RHEL 7.4 Update Services for SAP Solutions · python · FIXED · python-2.7.5-63.el7_4

sudo dnf upgrade --advisory=RHSA-2020:1346 rpm -q python

RHEL 7.5 Extended Update Support · python · FIXED · python-2.7.5-74.el7_5

sudo dnf upgrade --advisory=RHSA-2020:1268 rpm -q python

Amazon Linux 2 · see advisory · FIXED · ALAS2-2019-1291 · source

sudo yum update --advisory=ALAS2-2019-1291

Amazon Linux 1 · see advisory · FIXED · ALAS-2019-1324 · source

sudo yum update --advisory=ALAS-2019-1324

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: bugs.python.org/issue35907
Write-up: usn.ubuntu.com/4127-2/

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-2019-9948?

python: upgrade to 2.7.17, 3.5.8, 3.6.9, 3.7.4; leap: 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-2019-9948 being exploited?

CVE-2019-9948 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-2019-9948 affect?

CVE-2019-9948 affects python, leap, debian linux. Severity is critical (CVSS 9.1). urllib in Python 2.x through 2.7.16 supports the local_file: scheme, which makes it easier for remote attackers to bypass protection mechanisms that blacklist file: URIs, as demonstrated by triggering a urllib.urlopen('local_file:///etc/pas

How urgent is CVE-2019-9948?

Priority 71/100. Critical severity; EPSS top 4%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Python vulnerabilities · Ubuntu vulnerabilities · Debian vulnerabilities

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References

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