How severe is CVE-2021-42342?

CVE-2021-42342 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-42342 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 59% (99th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-42342?

CVE-2021-42342 affects Embedthis Goahead. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-42342?

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

When was CVE-2021-42342 published?

CVE-2021-42342 was published on 2021-10-14 and last updated on 2026-06-17.

CVE-2021-42342

CVE-2021-42342 is a critical-severity vulnerability in Embedthis Goahead with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 59% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-434.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 59% (99th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-434
Affected product: Embedthis Goahead
Published: 2021-10-14
Last modified: 2026-06-17

Description

An issue was discovered in GoAhead 4.x and 5.x before 5.1.5. In the file upload filter, user form variables can be passed to CGI scripts without being prefixed with the CGI prefix. This permits tunneling untrusted environment variables into vulnerable CGI scripts.

Frequently asked questions

What is CVE-2021-42342?: An issue was discovered in GoAhead 4.x and 5.x before 5.1.5. In the file upload filter, user form variables can be passed to CGI scripts without being prefixed with the CGI prefix. This permits tunneling untrusted environment variables into vulnerable CGI scripts.
How severe is CVE-2021-42342?: CVE-2021-42342 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-42342 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 59% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-42342?: CVE-2021-42342 affects Embedthis Goahead. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-42342?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-42342 published?: CVE-2021-42342 was published on 2021-10-14 and last updated on 2026-06-17.

References

https://github.com/embedthis/goahead/issues/305

Affected products (1)

cpe:2.3:a:embedthis:goahead:*:*:*:*:*:*:*:*

More vulnerabilities in Embedthis Goahead

CVE-2021-41615 — Critical (CVSS 9.8): websda.c in GoAhead WebServer 2.1.8 has insufficient nonce entropy because the nonce calculation relies on the…
CVE-2021-43298 — Critical (CVSS 9.8): The code that performs password matching when using 'Basic' HTTP authentication does not use a constant-time memcmp and…
CVE-2019-5096 — Critical (CVSS 9.8): An exploitable code execution vulnerability exists in the processing of multi-part/form-data requests within the base…
CVE-2017-1000471 — Critical (CVSS 9.8): EmbedThis GoAhead Webserver version 4.0.0 is vulnerable to a NULL pointer dereference in the CGI handler resulting in…
CVE-2017-5674 — Critical (CVSS 9.8): A vulnerability in a custom-built GoAhead web server used on Foscam, Vstarcam, and multiple white-label IP camera…
CVE-2020-15688 — High (CVSS 8.8): The HTTP Digest Authentication in the GoAhead web server before 5.1.2 does not completely protect against replay…

All CVEs affecting Embedthis Goahead →

Other CWE-434 (Unrestricted Upload of File with Dangerous Type) vulnerabilities

CVE-2026-48283 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Unrestricted Upload of File with Dangerous Type…
CVE-2026-48276 — Critical (CVSS 10.0): ColdFusion versions 2025.9, 2023.20 and earlier are affected by an Unrestricted Upload of File with Dangerous Type…
CVE-2026-57700 — Critical (CVSS 10.0): Unrestricted Upload of File with Dangerous Type vulnerability in Daan.Dev OMGF Pro allows Using Malicious Files. This…
CVE-2025-69129 — Critical (CVSS 10.0): Unauthenticated Arbitrary File Upload in WordPress & WooCommerce Scraper Plugin, Import Data from Any Site <= 1.0.7…
CVE-2026-40772 — Critical (CVSS 10.0): Unauthenticated Arbitrary File Upload in GeekyBot <= 1.2.2 versions.
CVE-2026-40412 — Critical (CVSS 10.0): Unrestricted upload of file with dangerous type in Azure Orbital Spatio allows an unauthorized attacker to execute code…

Browse all CWE-434 (Unrestricted Upload of File with Dangerous Type) vulnerabilities →