CVE-2021-3733

MEDIUMCVSS 6.5/10EPSS 4.67%

Last modified

CVE-2021-3733 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. There's a flaw in urllib's AbstractBasicAuthHandler class. An attacker who controls a malicious HTTP server that an HTTP client (such as web browser) connects to, could trigger a Regular Expression Denial of Service (ReDOS) during an authentication request with a specially crafted payload that is sent by the server to the client. EPSS estimates a 4.67% chance of exploitation in the next 30 days.

Description

There's a flaw in urllib's AbstractBasicAuthHandler class. An attacker who controls a malicious HTTP server that an HTTP client (such as web browser) connects to, could trigger a Regular Expression Denial of Service (ReDOS) during an authentication request with a specially crafted payload that is sent by the server to the client. The greatest threat that this flaw poses is to application availability.

Metrics

CVSS 3.1
6.5/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Probability
4.67%

90.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
PythonPython< 3.6.14
PythonPython>= 3.7.0, < 3.7.11
PythonPython>= 3.8.0, < 3.8.10
PythonPython>= 3.9.0, < 3.9.5
PythonPython3.10.0
RedhatCodeready Linux Builder8.0
RedhatCodeready Linux Builder For Ibm Z Systems8.0
RedhatCodeready Linux Builder For Power Little Endian8.0
RedhatEnterprise Linux8.0
RedhatEnterprise Linux Eus8.4
RedhatEnterprise Linux For Ibm Z Systems8.0
RedhatEnterprise Linux For Ibm Z Systems Eus8.4
RedhatEnterprise Linux For Power Little Endian8.0
RedhatEnterprise Linux For Power Little Endian Eus8.4
RedhatEnterprise Linux Server Aus8.4
RedhatEnterprise Linux Server For Power Little Endian Update Services For Sap Solutions8.4
RedhatEnterprise Linux Server Tus8.4
RedhatEnterprise Linux Server Update Services For Sap Solutions8.4
FedoraprojectExtra Packages For Enterprise Linux7.0
FedoraprojectFedora33
FedoraprojectFedora34
FedoraprojectFedora35
FedoraprojectFedora36
NetappManagement Services For Element Software And Netapp HciAll versions
NetappOntap Select Deploy Administration UtilityAll versions
NetappSolidfire\, Enterprise Sds \& Hci Storage NodeAll versions
NetappHci Compute Node FirmwareAll versions

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is CVE-2021-3733?
There's a flaw in urllib's AbstractBasicAuthHandler class. An attacker who controls a malicious HTTP server that an HTTP client (such as web browser) connects to, could trigger a Regular Expression Denial of Service (ReDOS) during an authentication request with a specially crafted payload that is sent by the server to the client. The greatest threat that this flaw poses is to application availability.
How severe is CVE-2021-3733?
CVE-2021-3733 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 4.67% probability of exploitation in the next 30 days.
How do I fix CVE-2021-3733?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-3733?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST