CVE-2021-22553Network attack vector

Server crash via immortal Git-over-HTTP sessions

Published Feb 17, 2021 · Updated Sep 16, 2024

Resource exhaustion in Gerrit Code Review allows remote attackers to crash the server through repeated Git-over-HTTP operations. GitOverHttpServlet creates an empty Jetty HTTP session for each request with an expiry of zero, so the session housekeeper never removes it. Unauthenticated access is sufficient; accumulated sessions consume the JVM heap until the Gerrit process runs out of memory and crashes.

CVSS severity6.5
Medium
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Gerrit Code Review allows remote attackers to crash the server through repeated Git-over-HTTP operations. GitOverHttpServlet creates an empty Jetty HTTP session for each request with an expiry of zero, so the session housekeeper never removes it. Unauthenticated access is sufficient; accumulated sessions consume the JVM heap until the Gerrit process runs out of memory and crashes.

The record

CVE
CVE-2021-22553
Published
Feb 17, 2021
Updated
Sep 16, 2024
Vendor
Gerrit Code Review
Product
Gerrit Code Review
Classifications
CWE-400, CWE-772, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 17, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <2.15.22
  2. Affected versionversion=unspecified <2.16.26
  3. Affected versionversion=unspecified <3.0.16
  4. Affected versionversion=unspecified <3.1.12
  5. Affected versionversion=unspecified <3.2.7
  6. Affected versionversion=unspecified <3.3.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Gerrit Code Review · Gerrit Code Reviewversion=unspecified <2.15.22; version=unspecified <2.16.26; version=unspecified <3.0.16; version=unspecified <3.1.12; version=unspecified <3.2.7; version=unspecified <3.3.2

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.5Google Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
CWE-772Missing Release of Resource after Effective Lifetime
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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