How severe is CVE-2021-4097?

CVE-2021-4097 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-4097 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-4097?

CVE-2021-4097 affects Phpservermonitor Php Server Monitor. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-4097?

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

When was CVE-2021-4097 published?

CVE-2021-4097 was published on 2021-12-12 and last updated on 2026-06-17.

CVE-2021-4097

CVE-2021-4097 is a medium-severity vulnerability in Phpservermonitor Php Server Monitor with a CVSS 3.x base score of 5.4. 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-93.

Key facts

Severity: Medium (CVSS 3.x base score 5.4)
CVSS v2: 5.8
EPSS exploit prediction: 1% (54th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-93
Affected product: Phpservermonitor Php Server Monitor
Published: 2021-12-12
Last modified: 2026-06-17

Description

phpservermon is vulnerable to Improper Neutralization of CRLF Sequences

Frequently asked questions

What is CVE-2021-4097?: phpservermon is vulnerable to Improper Neutralization of CRLF Sequences
How severe is CVE-2021-4097?: CVE-2021-4097 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-4097 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-4097?: CVE-2021-4097 affects Phpservermonitor Php Server Monitor. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-4097?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-4097 published?: CVE-2021-4097 was published on 2021-12-12 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:phpservermonitor:php_server_monitor:*:*:*:*:*:*:*:*

More vulnerabilities in Phpservermonitor Php Server Monitor

CVE-2018-18921 — Medium (CVSS 6.5): PHP Server Monitor before 3.3.2 has CSRF, as demonstrated by a Delete action.
CVE-2021-4241 — Low (CVSS 2.6): A vulnerability, which was classified as problematic, was found in phpservermon. Affected is the function…
CVE-2021-4240 — Low (CVSS 2.6): A vulnerability, which was classified as problematic, was found in phpservermon. This affects the function…

All CVEs affecting Phpservermonitor Php Server Monitor →

Other CWE-93 (CRLF Injection) vulnerabilities

CVE-2024-51501 — Critical (CVSS 10.0): Refit is an automatic type-safe REST library for .NET Core, Xamarin and .NET The various header-related Refit…
CVE-2026-45372 — Critical (CVSS 9.9): cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.44.0, when cpp-httplib's…
CVE-2026-11362 — Critical (CVSS 9.8): DataDog::DogStatsd versions through 0.07 for Perl allow metric injections from event tags. DataDog::DogStatsd does not…
CVE-2025-40671 — Critical (CVSS 9.3): SQL injection vulnerability in AES Multimedia's Gestnet v1.07. This vulnerability allows an attacker to retrieve,…
CVE-2026-11373 — Critical (CVSS 9.1): Net::Statsite::Client versions through 1.1.0 for Perl allow metric injections. Net::Statsite::Client is a client for…
CVE-2026-50638 — Critical (CVSS 9.1): Metrics::Any::Adapter::DogStatsd versions before 0.04 for Perl does not protect against metric injections. The statsd…

Browse all CWE-93 (CRLF Injection) vulnerabilities →