How severe is CVE-2021-20076?

CVE-2021-20076 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-20076 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (78th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-20076?

CVE-2021-20076 affects Tenable Tenable.sc. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-20076?

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-2021-20076 published?

CVE-2021-20076 was published on 2021-03-03 and last updated on 2026-06-17.

CVE-2021-20076

CVE-2021-20076 is a high-severity vulnerability in Tenable Tenable.sc with a CVSS 3.x base score of 8.8. 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-502.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 6.5
EPSS exploit prediction: 2% (78th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-502
Affected product: Tenable Tenable.sc
Published: 2021-03-03
Last modified: 2026-06-17

Description

Tenable.sc and Tenable.sc Core versions 5.13.0 through 5.17.0 were found to contain a vulnerability that could allow an authenticated, unprivileged user to perform Remote Code Execution (RCE) on the Tenable.sc server via Hypertext Preprocessor unserialization.

Frequently asked questions

What is CVE-2021-20076?: Tenable.sc and Tenable.sc Core versions 5.13.0 through 5.17.0 were found to contain a vulnerability that could allow an authenticated, unprivileged user to perform Remote Code Execution (RCE) on the Tenable.sc server via Hypertext Preprocessor unserialization.
How severe is CVE-2021-20076?: CVE-2021-20076 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-20076 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (78th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-20076?: CVE-2021-20076 affects Tenable Tenable.sc. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-20076?: 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-2021-20076 published?: CVE-2021-20076 was published on 2021-03-03 and last updated on 2026-06-17.

References

https://www.tenable.com/security/tns-2021-03

Affected products (1)

cpe:2.3:a:tenable:tenable.sc:*:*:*:*:*:*:*:*

More vulnerabilities in Tenable Tenable.sc

CVE-2021-44790 — Critical (CVSS 9.8): A carefully crafted request body can cause a buffer overflow in the mod_lua multipart parser (r:parsebody() called from…
CVE-2021-3711 — Critical (CVSS 9.8): In order to decrypt SM2 encrypted data an application is expected to call the API function EVP_PKEY_decrypt().…
CVE-2020-11656 — Critical (CVSS 9.8): In SQLite through 3.31.1, the ALTER TABLE implementation has a use-after-free, as demonstrated by an ORDER BY clause…
CVE-2019-19919 — Critical (CVSS 9.8): Versions of handlebars prior to 4.3.0 are vulnerable to Prototype Pollution leading to Remote Code Execution. Templates…
CVE-2019-19646 — Critical (CVSS 9.8): pragma.c in SQLite through 3.30.1 mishandles NOT NULL in an integrity_check PRAGMA command in certain cases of…
CVE-2021-40438 — Critical (CVSS 9.0): A crafted request uri-path can cause mod_proxy to forward the request to an origin server choosen by the remote user.…

All CVEs affecting Tenable Tenable.sc →

Other CWE-502 (Deserialization of Untrusted Data) vulnerabilities

CVE-2026-41104 — Critical (CVSS 10.0): Deserialization of untrusted data in Microsoft Planetary Computer Pro allows an unauthorized attacker to disclose…
CVE-2026-43633 — Critical (CVSS 10.0): HestiaCP versions 1.9.0 through 1.9.4 contain a deserialization vulnerability in the web terminal component caused by a…
CVE-2026-33819 — Critical (CVSS 10.0): Deserialization of untrusted data in Microsoft Bing allows an unauthorized attacker to execute code over a network.
CVE-2026-20131 — Critical (CVSS 10.0): A vulnerability in the web-based management interface of Cisco Secure Firewall Management Center (FMC) Software could…
CVE-2026-25632 — Critical (CVSS 10.0): EPyT-Flow is a Python package designed for the easy generation of hydraulic and water quality scenario data of water…
CVE-2025-14931 — Critical (CVSS 10.0): Hugging Face smolagents Remote Python Executor Deserialization of Untrusted Data Remote Code Execution Vulnerability.…

Browse all CWE-502 (Deserialization of Untrusted Data) vulnerabilities →