How severe is CVE-2026-42545?

CVE-2026-42545 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-42545 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-42545?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-42545 have an EU (EUVD) identifier?

Yes. CVE-2026-42545 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29856.

When was CVE-2026-42545 published?

CVE-2026-42545 was published on 2026-05-12 and last updated on 2026-06-17.

CVE-2026-42545

CVE-2026-42545 is a medium-severity vulnerability with a CVSS 3.x base score of 5.9. 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-248.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
EPSS exploit prediction: 0% (13th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-29856
Weakness: CWE-248
Published: 2026-05-12
Last modified: 2026-06-17

Description

Granian is a Rust HTTP server for Python applications. From 0.2.0 to 2.7.4, Granian aborts a worker process if a WSGI application returns an invalid HTTP response header name or value. The WSGI response conversion path uses .unwrap() on both the header name and header value constructors, so malformed output from the application becomes a process abort instead of a handled error. This vulnerability is fixed in 2.7.4.

Frequently asked questions

What is CVE-2026-42545?: Granian is a Rust HTTP server for Python applications. From 0.2.0 to 2.7.4, Granian aborts a worker process if a WSGI application returns an invalid HTTP response header name or value. The WSGI response conversion path uses .unwrap() on both the header name and header value constructors, so malformed output from the application becomes a process abort instead of a handled error. This vulnerability is fixed in 2.7.4.
How severe is CVE-2026-42545?: CVE-2026-42545 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-42545 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-42545?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-42545 have an EU (EUVD) identifier?: Yes. CVE-2026-42545 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29856.
When was CVE-2026-42545 published?: CVE-2026-42545 was published on 2026-05-12 and last updated on 2026-06-17.

References

https://github.com/emmett-framework/granian/security/advisories/GHSA-f5p7-9fr5-8jmj

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