CVE-2021-28373

The auth_internal plugin in Tiny Tiny RSS (aka tt-rss) before 2021-03-12 allows an attacker to log in via the OTP code without a valid password. NOTE: this issue only affected the git master branch for a short time. However, all end users are explicitly directed to use the git master branch in production. Semantic version numbers such as 21.03 appear to exist, but are automatically generated from the year and month. They are not releases.

Published: 2021-03-13 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-28373 is rated Moderate Risk (42.5/100): CVSS High severity, with low exploitation likelihood (EPSS 0.15%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-28373

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-11-21 0.16% 0.15% -0.02%
2 2025-11-18 0.15% 0.16% +0.02%
3 2025-03-30 — 0.15% —

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-28373

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-28373

OS Trackers for CVE-2021-28373

vendor priority summary link
debian unimportant CVE-2021-28373 unimportant priority: Debian including 1 source packages (tt-rss), 3 status rows across 3 suites (bookworm, bullseye, sid): resolved 3. https://security-tracker.debian.org/tracker/CVE-2021-28373
ubuntu medium CVE-2021-28373 medium priority: Ubuntu including 1 source packages (tt-rss), 6 status rows across 6 suites (bionic, focal, groovy, trusty, upstream, xenial): DNE 3, not-affected 3. https://ubuntu.com/security/CVE-2021-28373

Affected software / configurations for CVE-2021-28373

Vendor Product Version Raw CPE
tt-rss tiny_tiny_rss < 2021-03-12 cpe:2.3:a:tt-rss:tiny_tiny_rss:*:*:*:*:*:*:*:*

References for CVE-2021-28373

cvelogic Threat Intelligence