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.
CVE-2026-42304
HIGHNVD 7.57.5—Elevated
EchelonGraph scoreMEDIUM confidence
This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.4%, top 65% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, nvd
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.5Exploit: NoneExposed: 0
A fix is available — apply it.
- CVSS v3
- 7.5
- EG Score
- 7.5(medium)
- EPSS
- 34.9%
- KEV
- Not listed
Published
May 13, 2026
Last Modified
May 19, 2026
Advisory Details (1)
Auto-updated May 13, 2026🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available
Denial of Service (DoS) in twisted.names via Crafted DNS Compression Pointer Chains · Advisory · twisted/twisted · GitHub
https://github.com/twisted/twisted/security/advisories/GHSA-grgv-6hw6-v9g4Vendor Advisories for CVE-2026-42304(2)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Frequently asked(5)
What is CVE-2026-42304?
CVE-2026-42304 is a high vulnerability published on May 13, 2026. 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…
When was CVE-2026-42304 disclosed?
CVE-2026-42304 was first published in the National Vulnerability Database on May 13, 2026, with the most recent update on May 19, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-42304 actively exploited?
CVE-2026-42304 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 34.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-42304?
CVE-2026-42304 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-42304?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-42304, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-42304
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