Is CVE-2026-40562 in the CISA KEV catalog?

No. CVE-2026-40562 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-40562?

CVE-2026-40562 has a CVSS v3 base score of 7.5 (HIGH).

What is the EPSS score for CVE-2026-40562?

CVE-2026-40562 has an EPSS score of 0.32% (23th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2026-40562

HIGH

7.5

CVSS v3

NVD

Description

Gazelle versions through 0.49 for Perl allows HTTP Request Smuggling via Improper Header Precedence. Gazelle 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.

CWE-444

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityHigh

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Exploit Intelligence

0.32%probability of exploitation in 30 days

23rdpercentile

Low risk: more likely to be exploited than 23% of all known CVEs.

References

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-11.