Kiwi TCMS account confirmation open redirect through protocol-relative URLs
Summary
In Kiwi TCMS version 16.1, the fix for CVE-2026-54724 (open redirect via unvalidated next parameter) in the account confirmation endpoint is incomplete. The validation uses startswith("/") to check if the redirect URL is local, but this is bypassed by protocol-relative URLs like //evil.com which start with / but redirect the browser to an external attacker-controlled domain. 16.1’s incomplete mitigation still allows protocol-relative destinations and earlier releases lack the mitigation.
Vulnerable Code
In tcms/kiwi_auth/views.py, the Confirm view (line ~113):
def get_redirect_url(self, *args, **kwargs):
self.url = self.request.GET.get("next", reverse("core-views-index"))
if not self.url.startswith("/"):
self.url = reverse("core-views-index")
The check startswith("/") passes for //evil.com because it begins with /, but browsers interpret //evil.com as a protocol-relative URL that redirects to https://evil.com (or http://evil.com depending on the current page's protocol).
Proof of Concept
GET /confirm//?next=//evil.com/phishing HTTP/1.1
Host: kiwi.example.com
Response:
HTTP/1.1 302 Found
Location: //evil.com/phishing
The browser follows the redirect to https://evil.com/phishing.
Verification:
>>> url = "//evil.com/phishing"
>>> url.startswith("/")
True # passes the check!
Impact
An attacker can craft a confirmation link that, after the user confirms their account, redirects them to a phishing page. This is useful for:
- Credential phishing (fake login page on attacker domain)
- Malware delivery after trusted action
- Social engineering (user trusts the link because it's from the legitimate Kiwi TCMS instance)
The attack requires sending a crafted activation link to a user who is registering, or intercepting/predicting the activation key.
Suggested Fix
Use Django's url_has_allowed_host_and_scheme() utility instead of a simple startswith check:
from django.utils.http import url_has_allowed_host_and_scheme
def get_redirect_url(self, *args, **kwargs):
self.url = self.request.GET.get("next", reverse("core-views-index"))
if not url_has_allowed_host_and_scheme(
self.url,
allowed_hosts={self.request.get_host()},
require_https=self.request.is_secure(),
):
self.url = reverse("core-views-index")
This properly rejects protocol-relative URLs, absolute URLs to other hosts, and other bypass patterns.
Fixed in Version 16.2
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (6.1): severity, escalated by confirmed exploitation. This CVE's 6.1 is its impact severity (EG Severity), not escalated.
- EG Severity
- 6.1 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- Unknown (no EPSS on record)Unknown, not low: FIRST has published no EPSS probability for this CVE.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
The CVE record names the fixed release. Apply it within your standard update timelines.
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it