Is there a public exploit for CVE-2026-91920?

No public exploit for CVE-2026-91920 was found in Exploit-DB, Metasploit, Nuclei templates or public proof-of-concept repositories. That is an absence of evidence rather than proof that none exists.

How severe is CVE-2026-91920?

CVE-2026-91920 scores CVSS 6.5 (v3.1), rated medium. EPSS puts the chance of exploitation in the next 30 days at 0.24%.

6.5 Medium

A flaw was found in the ChunkReader component of the Undertow web server, which is used to handle chunked transfer encoding in HTTP…

CVE-2026-91920

A flaw was found in the ChunkReader component of the Undertow web server, which is used to handle chunked transfer encoding in HTTP requests. The issue occurs because a security check for the chunk size is performed before the value is shifted, allowing a specifically crafted 15-digit chunk size to bypass the limit and overflow into internal state flags. This can cause the server to terminate a request body prematurely and interpret the remaining data as a separate, smuggled request.

Assessment

CVSS: 6.5 (v3.1)
Severity: Medium
EPSS: 0.24% chance of exploitation in the next 30 days
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 30 October 2026
Last updated: 2 November 2026
Assigner: redhat

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

At the source

EUVD (ENISA)

References

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