Vulnary
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Critical· 9.8actively exploitedofficial fix available

CVE-2020-1938

Apache Tomcat’s default AJP connector can be exploited by attackers to read arbitrary files and execute code. The vulnerability allows remote code execution if the connector is reachable from untrusted networks. It is critical because it can compromise any Tomcat instance exposed to the internet.

publishedFeb 24, 2020
last modifiedAug 25, 2026
sourcesNVD · CISA-KEV
severity · cvss
9.8
critical · how bad it is
exploitation · epss
99%
100th percentile · chance of exploitation in 30 days
(ai-assisted) A model wrote this summary from the official data, so double-check it against the source before you act on it. Read the official advisory →
auto-deletes from the system
counting…on Sep 24, 2026

An official fix is available, so this entry is kept for 30 days and then removed automatically.

01

Who is affected

Apache Tomcat versions 7.0.0–7.0.99, 8.5.0–8.5.50, and 9.0.0.M1–9.0.0.30 that ship with the AJP connector enabled by default. Other products that embed Tomcat or the AJP connector, such as Apache Geode 1.12.0 and various Oracle Agile and communications products, are also affected.

02

Real-world impact

An attacker who can reach the AJP port can read any file on the server, upload malicious files, and have them executed as JSP, giving full control over the application and potentially the underlying operating system.

03

Why this severity

The CVSS score of 9.8 reflects that the vulnerability is remotely exploitable with no authentication, provides complete compromise of confidentiality, integrity, and availability, and can be triggered from any network location.

04

What to do about it

official fix available
recommended steps
  1. 01Upgrade Tomcat to version 9.0.31 or later, 8.5.51 or later, or 7.0.100 or later.
  2. 02If an upgrade is not possible, disable the AJP connector or restrict it to trusted IP addresses.
  3. 03Restart Tomcat to apply the changes.

CISA KEV required action and NVD vendor advisory

05

Timeline

  1. Feb 24, 2020 · Feb 24, 2020
    Published
    Disclosed and added to the National Vulnerability Database.
  2. Mar 3, 2022 · Mar 3, 2022
    Confirmed exploited (CISA KEV)
    CISA added it to the Known Exploited Vulnerabilities catalog — attackers are using it in the wild.
  3. Mar 17, 2022 · Mar 17, 2022
    CISA remediation deadline
    Federal agencies are required to remediate by this date.
  4. Aug 25, 2026 · 19d ago
    Advisory updated
    The NVD record was last revised.
  5. Aug 25, 2026 · 19d ago
    Official fix available
    A vendor patch or mitigation now exists — see the remediation steps above.
06

How it’s attacked

Attack vectorNetwork (remote)
Attack complexityLow
Privileges requiredNone
User interactionNone needed
ScopeUnchanged
Confidentiality impactHigh
Integrity impactHigh
Availability impactHigh
07

References & advisories

NVD advisory ↗CISA KEV catalog ↗Search advisories ↗
(ai-assisted) A model wrote this summary from the official data, so double-check it against the source before you act on it. Read the official advisory →