How severe is CVE-2026-42304?

CVE-2026-42304 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-2026-42304 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-42304?

CVE-2026-42304 primarily affects Twisted. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-42304?

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-2026-42304 have an EU (EUVD) identifier?

Yes. CVE-2026-42304 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30158.

When was CVE-2026-42304 published?

CVE-2026-42304 was published on 2026-05-13 and last updated on 2026-06-17.

CVE-2026-42304

CVE-2026-42304 is a high-severity vulnerability in Twisted 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-400.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (35th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-30158
Weakness: CWE-400
Affected product: Twisted
Published: 2026-05-13
Last modified: 2026-06-17

Description

Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.4.0rc2, the twisted.names module is vulnerable to a Denial of Service (DoS) attack via resource exhaustion during DNS name decompression. A remote, unauthenticated attacker can exploit this by sending a crafted TCP DNS packet containing deeply chained compression pointers. This flaw bypasses previous loop-prevention logic, causing the single-threaded Twisted reactor to hang while processing millions of recursive lookups, effectively freezing the server. This vulnerability is fixed in 26.4.0rc2.

Frequently asked questions

What is CVE-2026-42304?: Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.4.0rc2, the twisted.names module is vulnerable to a Denial of Service (DoS) attack via resource exhaustion during DNS name decompression. A remote, unauthenticated attacker can exploit this by sending a crafted TCP DNS packet containing deeply chained compression pointers. This flaw bypasses previous loop-prevention logic, causing the single-threaded Twisted reactor to hang while processing millions of recursive lookups, effectively freezing the server. This vulnerability is fixed in 26.4.0rc2.
How severe is CVE-2026-42304?: CVE-2026-42304 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-2026-42304 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-42304?: CVE-2026-42304 primarily affects Twisted. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-42304?: 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-2026-42304 have an EU (EUVD) identifier?: Yes. CVE-2026-42304 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30158.
When was CVE-2026-42304 published?: CVE-2026-42304 was published on 2026-05-13 and last updated on 2026-06-17.

References

https://github.com/twisted/twisted/security/advisories/GHSA-grgv-6hw6-v9g4

Affected products (2)

cpe:2.3:a:twisted:twisted:*:*:*:*:*:*:*:*
cpe:2.3:a:twisted:twisted:26.4.0:rc1:*:*:*:*:*:*

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