Is CVE-2026-23527 in the CISA KEV catalog?

No. CVE-2026-23527 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-23527?

CVE-2026-23527 has a CVSS v3 base score of 8.9 (HIGH).

What is the EPSS score for CVE-2026-23527?

CVE-2026-23527 has an EPSS score of 0.58% (43th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2026-23527

HIGH

8.9

CVSS v3

NVD

Description

H3 is a minimal H(TTP) framework built for high performance and portability. Prior to 1.15.5, there is a critical HTTP Request Smuggling vulnerability. readRawBody is doing a strict case-sensitive check for the Transfer-Encoding header. It explicitly looks for "chunked", but per the RFC, this header should be case-insensitive. This vulnerability is fixed in 1.15.5.

CWE-444

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeChanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityLow

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

Exploit Intelligence

0.58%probability of exploitation in 30 days

43rdpercentile

Moderate risk: more likely to be exploited than 43% 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 2026-04-13.