No exploitation reportedFix available

CVE-2021-21278

Q: Is CVE-2021-21278 actively exploited?

Active exploitation of CVE-2021-21278 has not been confirmed. Its EPSS score was 1.6% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-21278?

CVE-2021-21278 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

No exploitation reported by the sources we read.

Published2021-01-26
Fixed in2021-01-25
WeaknessCWE-74

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

RSSHub is an open source, easy to use, and extensible RSS feed generator. In RSSHub before version 7f1c430 (non-semantic versioning) there is a risk of code injection. Some routes use `eval` or `Function constructor`, which may be injected by the target site with unsafe code, causing server-side security issues The fix in version 7f1c430 is to temporarily remove the problematic route and added a `no-new-func` rule to eslint.

Timeline

dates in UTC

2021-01-2621:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-21278?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-21278?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Rsshub

Branch	Affected	Fixed in	Source
2021.x	< 2021-01-25	2021-01-25	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Rsshub to 2021-01-25

Advisories and patches

github.comPatch

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

CNACVSS 3.18.6read 2026-10-23
NVDCVSS 3.19.8read 2026-10-23
NVDCVSS 2.07.5read 2026-10-23
CNAweakness (CWE)CWE-74read 2026-10-23
FIRST EPSSEPSS score1.6 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published: 2021-01-26
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-21278?

Is CVE-2021-21278 actively exploited?

Active exploitation of CVE-2021-21278 has not been confirmed. Its EPSS score was 1.6% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-21278?

CVE-2021-21278 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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