CVE-2014-4650: The CGIHTTPServer module in Python 2.7.5 and 3.3.4 does not properly handle URLs in which URL encoding is used

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CRITICAL 9.8REMOTEWATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2014-4650 is a critical-severity flaw (CVSS 9.8) affecting python, software collections, enterprise linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The CGIHTTPServer module in Python 2.7.5 and 3.3.4 does not properly handle URLs in which URL encoding is used for path separators, which allows remote attackers to read script source code or conduct directory traversal attacks and execute unintended code via a crafted character sequence, as demonstrated by a %2f separator.

Why this priority

Critical severity
EPSS top 2%: 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	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	23.9% (top 2%)
CISA exploited list	No
Weakness	CWE-22
Published	2020-02-20
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: python · redhat

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 17:15 UTCPublished CVE record published
2026-06-17 00:10 UTCUpdated Record last modified

python python UPGRADE

Affected: >= 2.7.0 and < 2.7.8 · >= 3.2.0 and < 3.2.6 · >= 3.3.0 and < 3.3.6 · >= 3.4.0 and < 3.4.2

Fixed in: 2.7.8, 3.2.6, 3.3.6, 3.4.2

Safe to downgrade to: a release before 2.7.0

1. Check installed version

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

2. UPGRADE to 2.7.8 (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 2.7.0 (Debian / Ubuntu)

apt-cache madison python sudo apt install python=<VERSION_BEFORE_2.7.0> 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_2.7.0> 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.

redhat software collections MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy software-collections || rpm -q software-collections || software-collections --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

redhat enterprise linux MITIGATE

Affected: 5.0 · 6.0 · 7.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.0

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 · shotcut · FIXED · 26.10.30-1.fc46 · FEDORA-2026-7787c7fc2d · source

sudo dnf upgrade --advisory=FEDORA-2026-7787c7fc2d

RHEL 6 · python · FIXED · python-2.6.6-64.el6

sudo dnf upgrade --advisory=RHSA-2015:1330 rpm -q python

RHEL 7 · python · FIXED · python-2.7.5-34.el7

sudo dnf upgrade --advisory=RHSA-2015:2101 rpm -q python

RHEL 5 · python · DEFERRED

Amazon Linux 1 · see advisory · FIXED · ALAS-2015-621 · source

sudo yum update --advisory=ALAS-2015-621

Public exploits and detection

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

Exploit-DB: Python CGIHTTPServer - Encoded Directory Traversal

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-2014-4650?

python: upgrade to 2.7.8, 3.2.6, 3.3.6, 3.4.2; software collections: mitigate or apply the listed mitigation; enterprise linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2014-4650 being exploited?

CVE-2014-4650 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-2014-4650 affect?

CVE-2014-4650 affects python, software collections, enterprise linux. Severity is critical (CVSS 9.8). The CGIHTTPServer module in Python 2.7.5 and 3.3.4 does not properly handle URLs in which URL encoding is used for path separators, which allows remote attackers to read script source code or conduct directory traversal attacks and execute

How urgent is CVE-2014-4650?

Priority 74/100. Critical severity; EPSS top 2%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

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References

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