How severe is CVE-2021-35331?

CVE-2021-35331 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-35331 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-35331?

CVE-2021-35331 affects Tcl. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-35331?

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-2021-35331 published?

CVE-2021-35331 was published on 2021-07-05 and last updated on 2026-06-17.

CVE-2021-35331

CVE-2021-35331 is a high-severity vulnerability in Tcl with a CVSS 3.x base score of 7.8. 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-134.

Key facts

Severity: High (CVSS 3.x base score 7.8)
CVSS v2: 6.8
EPSS exploit prediction: 2% (74th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-134
Affected product: Tcl
Published: 2021-07-05
Last modified: 2026-06-17

Description

In Tcl 8.6.11, a format string vulnerability in nmakehlp.c might allow code execution via a crafted file. NOTE: multiple third parties dispute the significance of this finding

Frequently asked questions

What is CVE-2021-35331?: In Tcl 8.6.11, a format string vulnerability in nmakehlp.c might allow code execution via a crafted file. NOTE: multiple third parties dispute the significance of this finding
How severe is CVE-2021-35331?: CVE-2021-35331 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-35331 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-35331?: CVE-2021-35331 affects Tcl. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-35331?: 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-2021-35331 published?: CVE-2021-35331 was published on 2021-07-05 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:tcl:tcl:8.6.11:*:*:*:*:*:*:*

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CVE-2011-0270 — Critical (CVSS 10.0): Format string vulnerability in nnmRptConfig.exe in HP OpenView Network Node Manager (OV NNM) 7.51 and 7.53 allows…

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