CVE-2026-45336: HireFlow Authentication Bypass via Hard-Coded Flask Secret
TL;DR - HireFlow 1.2 and earlier use a hard-coded Flask
secret_key. - Attackers can forge signed session cookies and impersonate admin users. - Upgrade to HireFlow 1.3 immediately and invalidate existing sessions.
Vulnerability at a Glance
| Field | Value |
|---|---|
| CVE ID | CVE-2026-45336 |
| CVSS Score | 10.0 (NVD base score) |
| Attack Vector | Network |
| Privileges Required | None |
| Patch Available | Yes, fixed in HireFlow 1.3 |
CVE-2026-45336 is a critical authentication bypass in HireFlow, a web-based interview management platform maintained under the StratonWebDesigners namespace. The issue affects HireFlow 1.2 and earlier and is fixed in HireFlow 1.3. According to the NVD description, the flaw exists because the application uses a hard-coded Flask secret_key in app.py.
For defenders, the practical takeaway is straightforward: if your HireFlow deployment is internet-accessible and running 1.2 or earlier, you should assume that an attacker who can obtain the hard-coded secret can forge valid session cookies. Because the vulnerability enables unauthenticated privilege escalation to administrative access, this should be treated as an emergency patching case even though public exploitation has not been confirmed by CISA KEV at the time of writing.
What Is This Vulnerability?
At its core, CVE-2026-45336 is a failure in how application trust is established for user sessions. Flask commonly signs session data with a server-side secret. That signature is supposed to prevent clients from tampering with session contents. If the secret is hard-coded, especially in source code that may be public or otherwise recoverable, the integrity guarantee breaks down. An attacker can generate their own validly signed cookie that the application will accept as authentic.
The NVD description specifically states that attackers can forge cookies containing values such as role=admin and arbitrary user_id values. That means the application appears to trust authorization-relevant data supplied inside the signed session itself. Once the attacker knows the secret, they no longer need to steal a session from a real user. They can mint one from scratch and present themselves to the application as an authenticated administrative user.
Technical Notes
In Flask applications, signed client-side sessions often rely on a secret key like this:
app = Flask(__name__)
app.secret_key = "hardcoded-secret-value"
If the application stores security-relevant state directly in the session, a forged cookie may conceptually represent values like:
{
"user_id": 1,
"role": "admin",
"authenticated": true
}
That does not mean every vulnerable deployment uses those exact field names in exactly that format, but the NVD description confirms that role=admin and user_id are relevant values in this case.
Who Is Affected?
The confirmed affected range is HireFlow 1.2 and earlier. The fixed version is HireFlow 1.3. Those version details come directly from the NVD description and the referenced project release information. If you are running any deployment identified as 1.2, 1.1, 1.0, or another earlier build in that line, you should treat it as vulnerable unless you have independently verified that the hard-coded secret was removed and the application behavior materially changed.
Organizations most at risk are those exposing HireFlow to the internet for recruiters, hiring managers, or candidates. Because no prior authentication is required, external exposure significantly increases risk. Internal-only deployments are not safe by default either. If an internal user, contractor, or intruder can reach the application and recover the secret from code, a container image, a backup, or a published repository, they may be able to escalate to administrator.
The likely business impact is broad because HireFlow handles interview schedules, applicant records, and workflow decisions. An attacker with forged admin access may be able to view sensitive candidate data, alter interview pipelines, tamper with scheduling, or create persistence through application-level administrative functions. In HR and recruiting systems, that can quickly become both a security incident and a privacy issue.
CVSS Score Breakdown
The NVD assigns CVSS 10.0, which places this issue at the highest severity tier. The full vector string was not available in the research material provided, so defenders should avoid assuming individual metric values beyond what is supported by the observed behavior. Still, the published score is consistent with the characteristics of the flaw described by NVD: remote exploitation, no required privileges, and complete compromise of authentication trust.
Why such a high score? First, the attack is network-reachable if the web application is exposed. Second, no privileges are required, since the attacker can begin unauthenticated and generate their own session state. Third, the impact is not limited to a single low-value action. If cookie forgery grants admin access, confidentiality, integrity, and likely availability of the application’s workflows are all at risk.
In the absence of the full vector string, defenders should make a practical assumption: this is a near-worst-case web application flaw because it directly defeats authentication and authorization controls. Even without confirmed active exploitation, the combination of remote access, low attacker effort, and privileged outcomes justifies immediate remediation.
Exploitation Status
At the time of writing, CISA KEV does not list CVE-2026-45336, so there is no KEV-backed confirmation of active exploitation in the wild. That is an important distinction for incident prioritization and reporting. It means defenders should not claim known in-the-wild exploitation unless they have independent evidence from their own telemetry or another reputable source.
There is also no confirmed public PoC URL in the research material provided here. That said, absence of a public proof of concept should not be mistaken for difficulty. The weakness is conceptually simple: once the secret is known, session forgery is straightforward for anyone familiar with Flask session signing. In practical terms, this kind of flaw can often be weaponized rapidly even if no public PoC has yet been widely shared.
So the correct practitioner stance is: no confirmed public PoC from the provided sources, and no confirmed active exploitation in the wild from KEV, but exploitation should be assumed feasible with low effort. That should drive emergency patching, session invalidation, and post-upgrade validation.
How to Detect It
Detection is challenging because successful exploitation may look like a legitimate authenticated session from the application’s point of view. There may be no password spray, no failed logins, and no obvious brute-force activity. Instead, the signal may come from unexpected privileged sessions, sudden jumps into admin functionality, or session activity linked to impossible or inconsistent user identities.
Start by reviewing web access logs, reverse proxy logs, and application logs around administrative endpoints. Look for requests that access admin routes without corresponding login events, or sessions that appear to “become” admin users unexpectedly. If HireFlow or surrounding infrastructure logs cookie lengths, session identifiers, or unusual authentication transitions, correlate those with sensitive actions such as user management, schedule edits, or export/download operations.
Technical Notes
Example Apache or Nginx style paths to review for suspicious admin access:
/admin
/admin/
/admin/users
/admin/settings
/api/admin
A simple grep pattern for suspicious transitions where admin paths are hit without a nearby login event:
grep -E 'GET /admin|POST /admin|/api/admin' /var/log/nginx/access.log
If your application logs authentication events separately, compare admin-path access against login events from the same client IP or user context:
grep -E 'login|authenticated|auth success|admin' /var/log/hireflow/app.log
Example Splunk search to identify admin activity without a preceding login event from the same source IP in the previous 15 minutes:
index=web (uri_path="/admin" OR uri_path="/api/admin*")
| stats earliest(_time) as first_admin by src_ip
| join type=left src_ip [
search index=app ("login success" OR "authenticated")
| stats latest(_time) as last_login by src_ip
]
| eval gap=first_admin-last_login
| where isnull(last_login) OR gap > 900
| table src_ip first_admin last_login gap
If you can inspect Flask session behavior at the edge, a useful heuristic is to flag requests where a new or changed session cookie is immediately followed by privileged actions. In the absence of better telemetry, defenders should assume some exploitation attempts may be invisible and prioritize remediation over detection alone.
Mitigation and Patching
The primary fix is to upgrade to HireFlow 1.3, which is the version listed as fixed. If you are on HireFlow 1.2 and earlier, patching should be considered urgent. Because the issue involves a hard-coded signing secret, upgrading the application may not be enough by itself if old secrets remain valid or previously issued sessions remain trusted.
After upgrading, rotate any deployment secrets associated with session signing if the product now supports externalized secret configuration. You should also invalidate all active sessions so forged or previously signed cookies cannot continue to grant access. Review administrative accounts and recent changes in the application for signs of misuse, especially if the instance was internet-facing before patching.
If you cannot patch immediately, the best temporary workaround is to restrict access to the application behind a VPN, identity-aware proxy, or internal network controls. This is only a compensating measure. It does not remove the vulnerability; it only reduces the number of parties who can attempt exploitation.
Technical Notes
Upgrade commands will depend on how HireFlow is deployed. Because the authoritative source provided here confirms the fixed version but not a single canonical install method, use the command that matches your environment and verify the resulting version is 1.3.
Example Git-based deployment:
git fetch --tags
git checkout v1.3
pip install -r requirements.txt
systemctl restart hireflow
Example container-based workflow:
docker pull ghcr.io/stratonwebdesigners/hireflow:v1.3
docker stop hireflow
docker rm hireflow
docker run -d --name hireflow ghcr.io/stratonwebdesigners/hireflow:v1.3
If the application now reads the secret from an environment variable, set a unique random value and redeploy:
export HIREFLOW_SECRET_KEY="$(python3 -c 'import secrets; print(secrets.token_urlsafe(64))')"
systemctl restart hireflow
To force session invalidation, remove server-side session stores if used, or rotate the signing secret so existing client-side signed cookies become invalid. If you do not yet know whether the application has moved away from the hard-coded key, defenders should assume that simply restarting the app is insufficient.
References
The primary reference for this issue is the NVD record for CVE-2026-45336, which states that HireFlow 1.2 and earlier contain a hard-coded Flask secret_key in app.py, allowing attackers to forge session cookies and bypass authentication. That same description states that version 1.3 is fixed.
Additional reference points include the project’s v1.3 release and the linked GitHub security advisory under the StratonWebDesigners/HireFlow namespace. At the time of writing, CISA KEV does not list this CVE, so there is no KEV confirmation of active exploitation in the wild.
- NVD CVE record:
CVE-2026-45336 - HireFlow v1.3 release:
https://github.com/StratonWebDesigners/HireFlow/releases/tag/v1.3 - GitHub security advisory:
https://github.com/StratonWebDesigners/HireFlow/security/advisories/GHSA-x53g-jr84-jrv5
For further reading on related vulnerabilities, check out our articles on CVE-2026-28701 and Palo Alto Exploited Chrome Zero-Day.
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