CVE-2026-26273 is a critical-severity (CVSS 9.8) Information Exposure vulnerability in idno/known. A fix is available for idno/known — see the affected versions and patch details below.
Known affected by Account Takeover via Password Reset Token Leakage
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-26273.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-26273 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
idno/knownReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Summary
A Critical Broken Authentication vulnerability exists in Known 1.6.2. The application leaks the password reset token within a hidden HTML input field on the password reset page. This allows any unauthenticated attacker to retrieve the reset token for any user by simply querying the user's email, leading to full Account Takeover (ATO) without requiring access to the victim's email inbox.
Details
The vulnerability occurs within the password reset flow. When a reset is requested, the application generates a verification code. However, the subsequent reset page (/account/password/reset/) incorrectly reflects this code back to the client in the HTML source code.
Specifically, the sensitive token is embedded in: <input type="hidden" name="code" value="[SECRET_TOKEN]">
Because this page is accessible via a GET request using the victim's email as a parameter, an attacker can programmatically extract the token.
PoC
- The attacker asks for a password reset for the victim
-
The attacker makes the following curl command on the terminal using the victim's email, and is able to get the code that was sent as an hidden field in the HTML.
<img width="917" height="220" alt="image(2)" src="https://github.com/user-attachments/assets/af89ba3b-de56-4437-84b3-c1feb56d2348" /> -
With this code, the attacker is able to use it in order to reset the victim password.
<img width="1335" height="711" alt="image(3)" src="https://github.com/user-attachments/assets/498b8a2e-9eb2-4b50-bc35-26b0f2764c8d" />
- The attacker is able to login with the new password.
Impact
- An attacker can compromise any account on the platform, including administrative accounts, resulting in total loss of Confidentiality, Integrity, and Availability.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | idno/known | all versions | 1.6.3composer require idno/known:^1.6.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for idno/known, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update idno/known to 1.6.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-26273 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-26273 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-26273. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-26273 in your dependencies?
O3 Security finds CVE-2026-26273 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.