How severe is CVE-2026-42544?

CVE-2026-42544 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 none, integrity none, and availability high.

Is CVE-2026-42544 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-42544?

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-2026-42544 have an EU (EUVD) identifier?

Yes. CVE-2026-42544 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29855.

When was CVE-2026-42544 published?

CVE-2026-42544 was published on 2026-05-12 and last updated on 2026-06-17.

CVE-2026-42544

CVE-2026-42544 is a high-severity vulnerability 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-20.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (24th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-29855
Weakness: CWE-20
Published: 2026-05-12
Last modified: 2026-06-17

Description

Granian is a Rust HTTP server for Python applications. From 1.2.0 to 2.7.4, Granian aborts a worker process when an unauthenticated client sends a WebSocket upgrade request whose Sec-WebSocket-Protocol header contains non-ASCII bytes. The crash happens in Granian's WebSocket scope construction path, before the ASGI application is invoked. This vulnerability is fixed in 2.7.4.

Frequently asked questions

What is CVE-2026-42544?: Granian is a Rust HTTP server for Python applications. From 1.2.0 to 2.7.4, Granian aborts a worker process when an unauthenticated client sends a WebSocket upgrade request whose Sec-WebSocket-Protocol header contains non-ASCII bytes. The crash happens in Granian's WebSocket scope construction path, before the ASGI application is invoked. This vulnerability is fixed in 2.7.4.
How severe is CVE-2026-42544?: CVE-2026-42544 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 none, integrity none, and availability high.
Is CVE-2026-42544 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-42544?: 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-2026-42544 have an EU (EUVD) identifier?: Yes. CVE-2026-42544 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29855.
When was CVE-2026-42544 published?: CVE-2026-42544 was published on 2026-05-12 and last updated on 2026-06-17.

References

https://github.com/emmett-framework/granian/security/advisories/GHSA-vrg7-482j-p6f6

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