CVE-2025-31161
CrushFTP 10 before 10.8.4 and 11 before 11.3.1 allows authentication bypass and takeover of the crushadmin account (unless a DMZ proxy instance is used), as exploited in the wild in March and April 2025, aka "Unauthenticated HTTP(S) port access." A race condition exists in the AWS4-HMAC (compatible with S3) authorization method of the HTTP component of the FTP server. The server first verifies the existence of the user by performing a call to login_user_pass() with no password requirement. This will authenticate the session through the HMAC verification process and up until the server checks for user verification once more. The vulnerability can be further stabilized, eliminating the need for successfully triggering a race condition, by sending a mangled AWS4-HMAC header. By providing only the username and a following slash (/), the server will successfully find a username, which triggers the successful anypass authentication process, but the server will fail to find the expected SignedHeaders entry, resulting in an index-out-of-bounds error that stops the code from reaching the session cleanup. Together, these issues make it trivial to authenticate as any known or guessable user (e.g., crushadmin), and can lead to a full compromise of the system by obtaining an administrative account.
do firstApply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Can a WAF block it? Partly. Cloudflare publishes WAF a rule written for this CVE. Such rules block the known exploit requests and buy time, but attackers can change the request to get past them, so they do not replace the patch.
Cloudflare · 1 rule (Disabled) · since 22 Apr 2025
- CrushFTP - Auth Bypass - CVE:CVE-2025-31161 · Cloudflare Managed Ruleset
Also consider: patch · enable the vendor rule in block mode
Based on WAF vendor rules published for this CVE. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.
Is CVE-2025-31161 being exploited?
Yes. CVE-2025-31161 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2025-31161?
CVE-2025-31161 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2025-31161?
Yes. A fix has been recorded for CVE-2025-31161. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2025-31161 affect?
CVE-2025-31161 affects crushftp:crushftp. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
- affected>= 10 and < 10.8.4
- affected>= 11 and < 11.3.1
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.
public exploits
Public exploit code: 1 on Exploit-DB · 20 GitHub proofs of concept · 1 Nuclei template
- CrushFTP 11.3.1 - Authentication Bypass · remote · 18 May 2025
- CrushFTP - Authentication Bypass · detection template · critical
- Immersive-Labs-Sec/CVE-2025-31161 · 48 ★
- 0xgh057r3c0n/CVE-2025-31161 · 5 ★
- TX-One/CVE-2025-31161 · 2 ★
- f4dee-backup/CVE-2025-31161 · 2 ★
Listed so you can judge urgency, not as a recommendation to run anything. GitHub “proofs of concept” are unvetted: some are fake or carry malware. Exploit-DB marks the entries its staff verified.
cisa ssvc
- exploitation
- active
- automatable
- yes
- technical impact
- total
Assessed by CISA 15 Aug 2025 (SSVC 2.0.3).
timeline
- 3 Apr 2025Published
- 7 Apr 2025Added to CISA KEV (exploited in the wild) · 3 days later
- 8 Apr 2025First public exploit or proof of concept · 1 day later
- 28 Apr 2025CISA remediation due date (US federal agencies) · 20 days later
- 15 Aug 2025CISA SSVC assessment: exploitation active · 110 days (about 4 months) later
- 21 Oct 2025CVE record last updated · 67 days (about 2 months) later
- 2 Nov 2026Analysed by vulneraibility.com · 377 days (about 1 year) later
- Linkoutpost24.com /blog/crushftp-auth-bypass-vulnerability/
- Linkcrushftp.com /crush11wiki/Wiki.jsp?page=Update#section-Update-VulnerabilityInfo
- Linkprojectdiscovery.io /blog/crushftp-authentication-bypass
- Linkdarkreading.com /vulnerabilities-threats/disclosure-drama-clouds-crushftp-vulnerability-exploita
- Linkhuntress.com /blog/crushftp-cve-2025-31161-auth-bypass-and-post-exploitation
- Linkattackerkb.com /topics/k0EgiL9Psz/cve-2025-2825/rapid7-analysis
- Linkinfosecurity-magazine.com /news/crushftp-flaw-exploited-disclosure/
- Linkvicarius.io /vsociety/posts/cve-2025-31161-detect-crushftp-vulnerability
Show 2 more
- Linkvicarius.io /vsociety/posts/cve-2025-31161-mitigate-crushftp-vulnerability
- Linkcisa.gov /known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-31161
sources
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- CISA KEV catalog: exploitation, date added, due date
- CISA Vulnrichment (ADP): SSVC decision points
- FIRST EPSS: exploit probability and percentile
- Exploit-DB: published exploits
- Nuclei templates: detection templates
- PoC-in-GitHub: GitHub repositories that claim a proof of concept
- Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.