How severe is CVE-2021-26600?

CVE-2021-26600 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-2021-26600 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (92nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-26600?

CVE-2021-26600 affects Impresscms. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-26600?

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-2021-26600 published?

CVE-2021-26600 was published on 2022-03-28 and last updated on 2026-06-17.

CVE-2021-26600

CVE-2021-26600 is a critical-severity vulnerability in Impresscms with a CVSS 3.x base score of 9.8. 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-843.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 6% (92nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-843
Affected product: Impresscms
Published: 2022-03-28
Last modified: 2026-06-17

Description

ImpressCMS before 1.4.3 has plugins/preloads/autologin.php type confusion with resultant Authentication Bypass (!= instead of !==).

Frequently asked questions

What is CVE-2021-26600?: ImpressCMS before 1.4.3 has plugins/preloads/autologin.php type confusion with resultant Authentication Bypass (!= instead of !==).
How severe is CVE-2021-26600?: CVE-2021-26600 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-2021-26600 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (92nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-26600?: CVE-2021-26600 affects Impresscms. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-26600?: 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-2021-26600 published?: CVE-2021-26600 was published on 2022-03-28 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:impresscms:impresscms:*:*:*:*:*:*:*:*

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