How severe is CVE-2026-40560?

CVE-2026-40560 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2026-40560 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (38th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-40560?

CVE-2026-40560 affects Miyagawa Starman. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-40560?

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.

Does CVE-2026-40560 have an EU (EUVD) identifier?

Yes. CVE-2026-40560 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-26189.

When was CVE-2026-40560 published?

CVE-2026-40560 was published on 2026-04-29 and last updated on 2026-06-17.

CVE-2026-40560

CVE-2026-40560 is a high-severity vulnerability in Miyagawa Starman with a CVSS 3.x base score of 7.5. 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-444.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (38th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-26189
Weakness: CWE-444
Affected product: Miyagawa Starman
Published: 2026-04-29
Last modified: 2026-06-17

Description

Starman versions before 0.4018 for Perl allows HTTP Request Smuggling via Improper Header Precedence. Starman incorrectly prioritizes "Content-Length" over "Transfer-Encoding: chunked" when both headers are present in an HTTP request. Per RFC 7230 3.3.3, Transfer-Encoding must take precedence. An attacker could exploit this to smuggle malicious HTTP requests via a front-end reverse proxy.

Frequently asked questions

What is CVE-2026-40560?: Starman versions before 0.4018 for Perl allows HTTP Request Smuggling via Improper Header Precedence. Starman incorrectly prioritizes "Content-Length" over "Transfer-Encoding: chunked" when both headers are present in an HTTP request. Per RFC 7230 3.3.3, Transfer-Encoding must take precedence. An attacker could exploit this to smuggle malicious HTTP requests via a front-end reverse proxy.
How severe is CVE-2026-40560?: CVE-2026-40560 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-40560 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (38th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-40560?: CVE-2026-40560 affects Miyagawa Starman. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-40560?: 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.
Does CVE-2026-40560 have an EU (EUVD) identifier?: Yes. CVE-2026-40560 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-26189.
When was CVE-2026-40560 published?: CVE-2026-40560 was published on 2026-04-29 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:miyagawa:starman:*:*:*:*:*:perl:*:*

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