CVE-2023-31247Public exploitNetwork attack vector

Unauthenticated code execution via Host header overwrite

Published Nov 14, 2023 · Updated Nov 4, 2025

Memory corruption in uC-HTTP 3.01.01 allows remote attackers to execute code by sending an HTTP request with a crafted Host header. The HTTPsReq_HdrParse path permits a Host value equal to HostNameLenMax, then writes a null byte one byte past HostPtr and corrupts a heap free-list pointer. An unauthenticated attacker needs network access to an enabled HTTP server and suitable heap allocation state; successful exploitation permits arbitrary memory writes and code execution.

CVSS severity9.0
Critical
EPSS probability1.67%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory corruption in uC-HTTP 3.01.01 allows remote attackers to execute code by sending an HTTP request with a crafted Host header. The HTTPsReq_HdrParse path permits a Host value equal to HostNameLenMax, then writes a null byte one byte past HostPtr and corrupts a heap free-list pointer. An unauthenticated attacker needs network access to an enabled HTTP server and suitable heap allocation state; successful exploitation permits arbitrary memory writes and code execution.

The record

CVE
CVE-2023-31247
Published
Nov 14, 2023
Updated
Nov 4, 2025
Vendor
Sigma Designs
Product
Gecko Platform
Classifications
CWE-119, CWE-787, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 14, 2023CVE publishedPublication date reported by the CVE source.
  2. Nov 4, 2025Record 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=4.3.1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Sigma Designs · Gecko Platformversion=4.3.1.0
Weston Embedded Solutions · uC/HTTPversion=v3.01.01
Weston Embedded Solutions · Cs/NETversion=3.07.01

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.0Cisco TalosCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/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.

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 exploitPublished

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
CWE-787Out-of-bounds Write
T1190Exploit Public-Facing Application

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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