CVE-2026-78145Public exploitNetwork attack vector

Phishing redirects via tab normalization mismatch

Published Aug 23, 2026 · Updated Aug 23, 2026

Open redirect in CTFd 3.8.4 and earlier allows remote attackers to send users to an external site through a crafted next parameter. The _is_safe_url validator examines a tab-containing target before browser normalization, so Python treats it as same-origin while the browser resolves it as an external host. A user must follow the crafted login or registration link and complete that flow; the redirect can support phishing but does not alter server data.

CVSS severity4.3
Medium
EPSS probability0.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Open redirect in CTFd 3.8.4 and earlier allows remote attackers to send users to an external site through a crafted next parameter. The _is_safe_url validator examines a tab-containing target before browser normalization, so Python treats it as same-origin while the browser resolves it as an external host. A user must follow the crafted login or registration link and complete that flow; the redirect can support phishing but does not alter server data.

The record

CVE
CVE-2026-78145
Published
Aug 23, 2026
Updated
Aug 23, 2026
Vendor
CTFd LLC
Product
CTFd
Classifications
CWE-601, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 23, 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=3.8.0
  2. Affected versionversion=3.8.1
  3. Affected versionversion=3.8.2
  4. Affected versionversion=3.8.3
  5. Affected versionversion=3.8.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

CTFd LLC · CTFdversion=3.8.0; version=3.8.1; version=3.8.2; version=3.8.3; version=3.8.4

Published CVSS scores

4.3VulDBCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
5.0VulDBAV:N/AC:L/Au:N/C:N/I:P/A:N
2.1VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E: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 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-601URL Redirection to Untrusted Site ('Open Redirect')
T1204.001User Execution: Malicious Link

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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