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CVE-2021-3733

Public exploit available. Not confirmed exploited in the wild yet. A vendor fix is available.

CVSS 3.16.5MediumEPSS percentile91st4.7% chance in 30 daysCISA KEVNot listedNo confirmed exploitation
Public exploit: 1 sourceFixVendor fixNo build named by the sources

Published Updated Sources: CVE.org, NVD, BDU, CSAF

NVD CVE.org

What to do

The vendor has published a fix. Version details are below where the sources state them.

Check it yourselfA free OpenVAS check exists for this CVE. Run it against your hosts.Is your organisation exposed?Request an assessment to establish which checks fit your systems.

What it is

From the CVE record

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.

In plain language

No plain-language summary for this CVE yet.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS91st
Public exploit
CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

1 source with a proof of concept or module.

Exploit links, PoCs and Metasploit modules after sign-in
EPSS

4.7% chance of exploitation activity in the next 30 days, which ranks it in the 91st percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

The patch came 123 days before any public exploit.

  1. OpenVAS check added
  2. Public exploit / PoCsource: other
  3. Patch availablerecord updated
  4. Publishedweakness classified, att&ck mapped

Affected products

And 9 more affected products. See all after sign-in

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

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

Scored 6.5 by NVD.

How it is reached

  • Attack Vector NetworkExploitable remotely over the network without any special conditions
  • Attack Complexity LowNo special conditions — the attack can be reliably reproduced
  • Privileges Required LowRequires basic user-level privileges
  • User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

  • Scope UnchangedImpact is limited to the vulnerable component itself

Impact if exploited

  • Confidentiality NoneNo confidentiality impact
  • Integrity NoneNo integrity impact
  • Availability HighTotal denial of service — the component is completely unavailable

Weaknesses

ATT&CK techniques

Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.

Sources

References in the record

And 34 more references. See all after sign-in

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