CVE-2024-23826Public exploitNetwork attack vector

Authenticated server hang via unbounded Unicode normalization

Published Jan 29, 2024 · Updated Jun 2, 2025

Resource exhaustion in SPbSU SE Site before 2024.01.29 allows remote authenticated users to hang a Windows server via an avatar filename. The upload_avatar handler passes an unrestricted filename to secure_filename, whose NFKD normalization performs costly work on attacker-controlled Unicode. Avatar-upload access and user interaction are required; a sufficiently large filename leaves the web application unable to process further requests.

CVSS severity6.8
Medium
EPSS probability0.45%
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 SPbSU SE Site before 2024.01.29 allows remote authenticated users to hang a Windows server via an avatar filename. The upload_avatar handler passes an unrestricted filename to secure_filename, whose NFKD normalization performs costly work on attacker-controlled Unicode. Avatar-upload access and user interaction are required; a sufficiently large filename leaves the web application unable to process further requests.

The record

CVE
CVE-2024-23826
Published
Jan 29, 2024
Updated
Jun 2, 2025
Vendor
SPbU Software Engineering
Product
SPbSU SE Site
Classifications
CWE-770, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 29, 2024CVE publishedPublication date reported by the CVE source.
  2. Jun 2, 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=< 2024.01.29

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

SPbU Software Engineering · SPbSU SE Siteversion=< 2024.01.29

Published CVSS scores

5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H
6.8GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
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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