CVE-2023-28391Public exploitNetwork attack vector

Remote code execution via off-by-one 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 a crafted HTTP header to an embedded server. HTTPsReq_HdrParse accepts a non-special header value whose length equals DataLenMax, then writes its NUL terminator one byte beyond the allocated buffer. The request must reach a server configured to retain that header; the overwrite can corrupt the heap freelist and enable an attacker-controlled allocation.

CVSS severity9.0
Critical
EPSS probability1.47%
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 a crafted HTTP header to an embedded server. HTTPsReq_HdrParse accepts a non-special header value whose length equals DataLenMax, then writes its NUL terminator one byte beyond the allocated buffer. The request must reach a server configured to retain that header; the overwrite can corrupt the heap freelist and enable an attacker-controlled allocation.

The record

CVE
CVE-2023-28391
Published
Nov 14, 2023
Updated
Nov 4, 2025
Vendor
Sigma Designs
Product
Gecko Platform
Classifications
CWE-787, CWE-119, 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=3.01.01; version=v3.01.01
Weston Embedded Solutions · Cs/NETversion=3.07.01

Published CVSS scores

9.0Cisco TalosCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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-787Out-of-bounds Write
CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
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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