CVE-2026-2940Public exploitNetwork attack vector

Unauthenticated server crash via oversized URI

Published Feb 22, 2026 · Updated Feb 22, 2026

Out-of-bounds write in Tiny Web Server allows remote attackers to crash the server by requesting an oversized nonexistent URI. In client_error(), sprintf() copies the unvalidated request-derived filename into the fixed 8,192-byte linebuf stack buffer without a length bound. An unauthenticated HTTP GET with a missing-file URI around 8,180 bytes reaches the error path; the published demonstration confirms a stack-buffer-overflow crash, while code execution or disclosure is not demonstrated.

CVSS severity7.3
High
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in Tiny Web Server allows remote attackers to crash the server by requesting an oversized nonexistent URI. In client_error(), sprintf() copies the unvalidated request-derived filename into the fixed 8,192-byte linebuf stack buffer without a length bound. An unauthenticated HTTP GET with a missing-file URI around 8,180 bytes reaches the error path; the published demonstration confirms a stack-buffer-overflow crash, while code execution or disclosure is not demonstrated.

The record

CVE
CVE-2026-2940
Published
Feb 22, 2026
Updated
Feb 22, 2026
Vendor
Zaher1307
Product
Tiny Web Server
Classifications
CWE-119, CWE-787, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 22, 2026Record 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=8d77b1044a0ca3a5297d8726ac8aa2cf944d481b

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Zaher1307 · Tiny Web Serverversion=8d77b1044a0ca3a5297d8726ac8aa2cf944d481b

Published CVSS scores

5.5INCIBE-CERTCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
7.3VulDBCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
7.5VulDBAV:N/AC:L/Au:N/C:P/I:P/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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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