Description
Course-tencent-cloud through 2.0.1 contains an improper restriction of authentication attempts vulnerability that allows unauthenticated attackers to brute force 6-digit SMS/email verification codes, which are never invalidated or attempt-limited. Attackers who know a victim's phone or email can trigger a code and rotate source IPs against the password reset and verify login endpoints to take over accounts.
References5
- github.com/xiaochong0302/course-tencent-cloud/blob/v2.0.1/app/S…
- github.com/xiaochong0302/course-tencent-cloud/blob/v2.0.1/app/S…
- hackmd.io/@hieuPenguinnn/ctc-verify-code-brute-force-account-ta…
- www.vulncheck.com/advisories/course-tencent-cloud-through-2.0.1…
- hackmd.io/@hieuPenguinnn/ctc-verify-code-brute-force-account-ta…
Metrics
- CVSS 3.1
-
7.4
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N - CVSS 4.0
-
9.1
CRITICAL
Score source: CNA
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 1% percentile: 45 · as of 10 November 2026
- CWE
- CWE-307
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.