THREATPORT/VULNERABILITY/CVE-2021-3733
MEDIUM SEVERITY

CVE-2021-3733

Python vulnerability

CVSS
6.5
EPSS
4.8%
EPSS pct
91th
Exploited
No known
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.
Affected vendor
Python
Affected product
Python
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness type (CWE)
  • CWE-400 — Uncontrolled Resource Consumption
Published
2022-03-10

Risk analysis

Based on its CVSS vector, this vulnerability is exploitable over the network, low attack complexity, requiring low privileges, no user interaction. Successful exploitation leads to high impact to availability.

Its EPSS score of 4.8% reflects a lower probability of exploitation activity in the wild over the next 30 days, placing it above 91% of all scored CVEs.

Check your external exposure to CVE-2021-3733

  • Confirm whether Python Python is running on any internet-facing host or subdomain.
  • Match discovered service fingerprints against the version affected by CVE-2021-3733.
  • Prioritise remediation if the asset is public, business-critical, or near authentication/payment flows.

How ThreatPort helps with CVE-2021-3733

ThreatPort's external attack surface scanner checks your internet-facing assets — agentlessly, from the outside in — for the exposed services and versions that CVE-2021-3733 affects, then prioritises the finding by real risk using CISA KEV and FIRST.org EPSS.

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