THREATPORT/VULNERABILITY/CVE-2021-30639
HIGH SEVERITY

CVE-2021-30639

Tomcat vulnerability

CVSS
7.5
EPSS
6.9%
EPSS pct
93th
Exploited
No known
A vulnerability in Apache Tomcat allows an attacker to remotely trigger a denial of service. An error introduced as part of a change to improve error handling during non-blocking I/O meant that the error flag associated with the Request object was not reset between requests. This meant that once a non-blocking I/O error occurred, all future requests handled by that request object would fail. Users were able to trigger non-blocking I/O errors, e.g. by dropping a connection, thereby creating the possibility of triggering a DoS. Applications that do not use non-blocking I/O are not exposed to this vulnerability. This issue affects Apache Tomcat 10.0.3 to 10.0.4; 9.0.44; 8.5.64.
Affected vendor
Apache
Affected product
Tomcat
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness type (CWE)
Published
2021-07-12

Risk analysis

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

Its EPSS score of 6.9% reflects a lower probability of exploitation activity in the wild over the next 30 days, placing it above 93% of all scored CVEs.

Check your external exposure to CVE-2021-30639

  • Confirm whether Apache Tomcat is running on any internet-facing host or subdomain.
  • Match discovered service fingerprints against the version affected by CVE-2021-30639.
  • Prioritise remediation if the asset is public, business-critical, or near authentication/payment flows.

How ThreatPort helps with CVE-2021-30639

ThreatPort's external attack surface scanner checks your internet-facing assets — agentlessly, from the outside in — for the exposed services and versions that CVE-2021-30639 affects, then prioritises the finding by real risk using CISA KEV and FIRST.org EPSS.

Run a free external exposure scan

Are you exposed to CVE-2021-30639?

Run an instant, non-intrusive external scan to check your attack surface for CVE-2021-30639.

Start free scan

No credit card. Agentless.

Related vulnerabilities

HIGH
CVE-2015-4060
Connectpro vulnerability
HIGH
CVE-2015-4067
Netvault Backup vulnerability
HIGH
CVE-2015-4069
Arcserve Unified Data Protection vulnerability