How severe is CVE-2021-28373?

CVE-2021-28373 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2021-28373 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (56th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-28373?

CVE-2021-28373 affects Tt-rss Tiny Tiny Rss. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-28373?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-28373 published?

CVE-2021-28373 was published on 2021-03-13 and last updated on 2026-06-17.

CVE-2021-28373

CVE-2021-28373 is a high-severity vulnerability in Tt-rss Tiny Tiny Rss with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-863.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 1% (56th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-863
Affected product: Tt-rss Tiny Tiny Rss
Published: 2021-03-13
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2021-28373?: CVE-2021-28373 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2021-28373 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (56th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-28373?: CVE-2021-28373 affects Tt-rss Tiny Tiny Rss. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-28373?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-28373 published?: CVE-2021-28373 was published on 2021-03-13 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:tt-rss:tiny_tiny_rss:*:*:*:*:*:*:*:*

More vulnerabilities in Tt-rss Tiny Tiny Rss

CVE-2020-25787 — Critical (CVSS 9.8): An issue was discovered in Tiny Tiny RSS (aka tt-rss) before 2020-09-16. It does not validate all URLs before…
CVE-2017-16896 — Critical (CVSS 9.8): A SQL injection in classes/handler/public.php in the forgotpass component of Tiny Tiny RSS 17.4 exists via the login…
CVE-2020-25788 — High (CVSS 8.1): An issue was discovered in Tiny Tiny RSS (aka tt-rss) before 2020-09-16. imgproxy in plugins/af_proxy_http/init.php…
CVE-2020-25789 — Medium (CVSS 6.1): An issue was discovered in Tiny Tiny RSS (aka tt-rss) before 2020-09-16. The cached_url feature mishandles JavaScript…
CVE-2017-1000035 — Medium (CVSS 6.1): Tiny Tiny RSS before 829d478f is vulnerable to XSS window.opener attack

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Browse all CWE-863 (Incorrect Authorization) vulnerabilities →