CVE-2021-4433Public exploitNetwork attack vector

Remote service interruption via crafted HEAD request

Published Jan 18, 2024 · Updated Oct 23, 2024

Improper resource release in KarjaSoft Sami HTTP Server 2.0 allows remote attackers to interrupt service through a crafted HEAD request. The HTTP HEAD request handler fails to release an unspecified resource after processing attacker-controlled input; public records omit the function and exact malformed field. No authentication or user interaction is required, and the reported consequence is limited to web-service availability, with no reported code execution or data access.

CVSS severity7.5
High
EPSS probability1.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper resource release in KarjaSoft Sami HTTP Server 2.0 allows remote attackers to interrupt service through a crafted HEAD request. The HTTP HEAD request handler fails to release an unspecified resource after processing attacker-controlled input; public records omit the function and exact malformed field. No authentication or user interaction is required, and the reported consequence is limited to web-service availability, with no reported code execution or data access.

The record

CVE
CVE-2021-4433
Published
Jan 18, 2024
Updated
Oct 23, 2024
Vendor
KarjaSoft
Product
Sami HTTP Server
Classifications
CWE-404, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 18, 2024CVE publishedPublication date reported by the CVE source.
  2. Oct 23, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=2.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

KarjaSoft · Sami HTTP Serverversion=2.0

Published CVSS scores

5.3VulDBCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
5.0VulDBAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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.

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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 exploitPublished

Weakness, pattern, technique

CWE-404Improper Resource Shutdown or Release
T1499.004Application or System Exploitation

Public exploit references

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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