CVE-2026-25222
Published: 02 February 2026
Summary
CVE-2026-25222 is a high-severity Exposure of Sensitive Information to an Unauthorized Actor (CWE-200) vulnerability in Polarlearn Polarlearn. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Email Addresses (T1589.002); ranked at the 11.3th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
Threat & Defense at a Glance
Threat & Defense Details
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Automated marking applies security attributes to system outputs, making it harder for attackers to exploit unmarked sensitive information leading to unauthorized exposure.
Proper attribute retention and permitted-value enforcement limits unauthorized actors from accessing sensitive information lacking correct labels.
Prevents unauthorized exposure of sensitive information by prohibiting untrusted external systems from processing or storing it.
By enforcing authorization matching prior to sharing, the control reduces the risk of exposing sensitive information to unauthorized actors.
Review and removal of nonpublic information from publicly accessible systems directly prevents exposure of sensitive data to unauthorized actors.
Data mining protection mechanisms detect and block unauthorized bulk extraction of sensitive data, directly mitigating exposure to unauthorized actors.
Literacy training teaches users to recognize and avoid actions that result in unauthorized exposure of sensitive information.
Retaining and monitoring training records confirms personnel have completed privacy and security awareness training on handling sensitive data, reducing the chance of unauthorized exposure due to lack of knowledge.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Timing side-channel directly enables remote enumeration of valid email addresses/accounts (T1589.002, T1087.003) without authentication.
NVD Description
PolarLearn is a free and open-source learning program. In 0-PRERELEASE-15 and earlier, a timing attack vulnerability in the sign-in process allows unauthenticated attackers to determine if a specific email address is registered on the platform. By measuring the response time…
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of the login endpoint, an attacker can distinguish between valid and invalid email addresses. This occurs because the server only performs the computationally expensive Argon2 password hashing if the user exists in the database. Requests for existing users take significantly longer (~650ms) than requests for non-existent users (~160ms).
Deeper analysisAI
CVE-2026-25222 is a timing attack vulnerability affecting PolarLearn, a free and open-source learning program, in versions 0-PRERELEASE-15 and earlier. The issue resides in the sign-in process, where unauthenticated attackers can determine if a specific email address is registered on the platform by measuring response times from the login endpoint. This discrepancy arises because the server performs computationally expensive Argon2 password hashing only for existing users, resulting in significantly longer response times—approximately 650ms for valid emails versus 160ms for non-existent ones. The vulnerability is rated with a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N) and maps to CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor).
Unauthenticated remote attackers can exploit this vulnerability over the network with low complexity and no privileges required. By sending repeated login requests with targeted email addresses and timing the responses, attackers can reliably enumerate valid user accounts registered on the platform. This enables harvesting of email lists, which could facilitate further attacks such as phishing, credential stuffing, or social engineering, though it does not allow direct access to passwords or other account data.
Mitigation is detailed in the PolarLearn GitHub security advisory (GHSA-wcr9-mvr9-4qh5) and addressed in commit 6c276855172c7310cce0df996cb47ffe0d886741, which likely implements consistent timing behavior in the authentication flow to prevent side-channel leakage. Security practitioners should update to a patched version beyond 0-PRERELEASE-15 and review login endpoints for similar timing oracle issues in custom implementations.
Details
- CWE(s)