How severe is CVE-2025-40907?

CVE-2025-40907 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2025-40907 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (40th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-40907?

CVE-2025-40907 affects Fastcgi Fcgi. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-40907?

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

Does CVE-2025-40907 have an EU (EUVD) identifier?

Yes. CVE-2025-40907 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-15438.

When was CVE-2025-40907 published?

CVE-2025-40907 was published on 2025-05-16 and last updated on 2026-06-17.

CVE-2025-40907

CVE-2025-40907 is a medium-severity vulnerability in Fastcgi Fcgi with a CVSS 3.x base score of 5.3. 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-190.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
EPSS exploit prediction: 1% (40th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-15438
Weakness: CWE-190
Affected product: Fastcgi Fcgi
Published: 2025-05-16
Last modified: 2026-06-17

Description

FCGI versions 0.44 through 0.82, for Perl, include a vulnerable version of the FastCGI fcgi2 (aka fcgi) library. The included FastCGI library is affected by CVE-2025-23016, causing an integer overflow (and resultant heap-based buffer overflow) via crafted nameLen or valueLen values in data to the IPC socket. This occurs in ReadParams in fcgiapp.c.

Frequently asked questions

What is CVE-2025-40907?: FCGI versions 0.44 through 0.82, for Perl, include a vulnerable version of the FastCGI fcgi2 (aka fcgi) library. The included FastCGI library is affected by CVE-2025-23016, causing an integer overflow (and resultant heap-based buffer overflow) via crafted nameLen or valueLen values in data to the IPC socket. This occurs in ReadParams in fcgiapp.c.
How severe is CVE-2025-40907?: CVE-2025-40907 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2025-40907 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (40th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-40907?: CVE-2025-40907 affects Fastcgi Fcgi. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-40907?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-40907 have an EU (EUVD) identifier?: Yes. CVE-2025-40907 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-15438.
When was CVE-2025-40907 published?: CVE-2025-40907 was published on 2025-05-16 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:fastcgi:fcgi:*:*:*:*:*:perl:*:*

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