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Improper Restriction of Operations within the Bounds of a Memory Buffer in Apache Tomcat

High severity GitHub Reviewed Published Feb 8, 2022 to the GitHub Advisory Database • Updated May 20, 2026

Package

maven org.apache.tomcat:tomcat (Maven)

Affected versions

>= 10.0.0-M1, <= 10.0.0-M5
>= 9.0.0.M5, < 9.0.36
>= 8.5.1, < 8.5.56

Patched versions

10.0.0-M6
9.0.36
8.5.56
maven org.apache.tomcat:tomcat-coyote (Maven)
>= 10.0.0-M1, <= 10.0.0-M5
>= 9.0.0.M5, < 9.0.36
>= 8.5.1, < 8.5.56
10.0.0-M6
9.0.36
8.5.56

Description

An h2c direct connection to Apache Tomcat 10.0.0-M1 to 10.0.0-M6, 9.0.0.M5 to 9.0.36 and 8.5.1 to 8.5.56 did not release the HTTP/1.1 processor after the upgrade to HTTP/2. If a sufficient number of such requests were made, an OutOfMemoryException could occur leading to a denial of service.

References

Published by the National Vulnerability Database Jul 14, 2020
Reviewed Apr 12, 2021
Published to the GitHub Advisory Database Feb 8, 2022
Last updated May 20, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(99th percentile)

Weaknesses

Improper Restriction of Operations within the Bounds of a Memory Buffer

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data. Learn more on MITRE.

NULL Pointer Dereference

The product dereferences a pointer that it expects to be valid but is NULL. Learn more on MITRE.

CVE ID

CVE-2020-13934

GHSA ID

GHSA-vf77-8h7g-gghp

Source code

Credits

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