How severe is CVE-2021-3374?

CVE-2021-3374 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2021-3374 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 14% (96th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3374?

CVE-2021-3374 affects Rstudio Shiny Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-3374?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-3374 published?

CVE-2021-3374 was published on 2021-04-02 and last updated on 2026-06-17.

CVE-2021-3374

CVE-2021-3374 is a medium-severity vulnerability in Rstudio Shiny Server with a CVSS 3.x base score of 5.3. Its EPSS exploit-prediction score of 14% places it in the 96th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-22.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 5.0
EPSS exploit prediction: 14% (96th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-22
Affected product: Rstudio Shiny Server
Published: 2021-04-02
Last modified: 2026-06-17

Description

Directory traversal in RStudio Shiny Server before 1.5.16 allows attackers to read the application source code, involving an encoded slash.

Frequently asked questions

What is CVE-2021-3374?: Directory traversal in RStudio Shiny Server before 1.5.16 allows attackers to read the application source code, involving an encoded slash.
How severe is CVE-2021-3374?: CVE-2021-3374 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2021-3374 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 14% (96th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3374?: CVE-2021-3374 affects Rstudio Shiny Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-3374?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-3374 published?: CVE-2021-3374 was published on 2021-04-02 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:rstudio:shiny_server:*:*:*:*:pro:*:*:*

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