CVE-2025-31161Known exploitationPublic exploitNetwork attack vector

Unauthenticated account takeover via AWS4-HMAC flag confusion

Published Apr 3, 2025 · Updated Oct 21, 2025

Authentication bypass in CrushFTP 10 before 10.8.4 and 11 before 11.3.1 allows remote attackers to take over known user accounts. The HTTP S3 loginCheckHeaderAuth path passes a password-lookup flag to login_user_pass as anyPass, while a malformed AWS4-HMAC header prevents session cleanup. Exploitation requires a known or guessable username and direct HTTP(S) access without a DMZ proxy; taking over crushadmin grants administrative control.

CVSS severity9.8
Critical
EPSS probability99.97%
Next 30 days · Nov 1, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in CrushFTP 10 before 10.8.4 and 11 before 11.3.1 allows remote attackers to take over known user accounts. The HTTP S3 loginCheckHeaderAuth path passes a password-lookup flag to login_user_pass as anyPass, while a malformed AWS4-HMAC header prevents session cleanup. Exploitation requires a known or guessable username and direct HTTP(S) access without a DMZ proxy; taking over crushadmin grants administrative control.

The record

CVE
CVE-2025-31161
Published
Apr 3, 2025
Updated
Oct 21, 2025
Vendor
CrushFTP
Product
CrushFTP
Classifications
CWE-305, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 28, 2025Exploitation reportedCrushFTP customer compromise reports
  2. Apr 3, 2025CVE publishedPublication date reported by the CVE source.
  3. Oct 21, 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=10 <10.8.4
  2. Affected versionversion=11 <11.3.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

CrushFTP · CrushFTPversion=10 <10.8.4; version=11 <11.3.1

Published CVSS scores

9.8NVDCVSS: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.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsShadowserver observations through Sep 28, 2026. Gaps indicate unavailable data.
Sep 22, 2026Sep 28, 2026
View daily counts
Reporting dayUnique IPs
Sep 22, 2026Unavailable
Sep 23, 20261
Sep 24, 2026Unavailable
Sep 25, 2026Unavailable
Sep 26, 2026Unavailable
Sep 27, 2026Unavailable
Sep 28, 2026Unavailable
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitPublished

Weakness, pattern, technique

CWE-305Authentication Bypass by Primary Weakness
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

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Your stack

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