high7.5
CVE-2026-42304
Twisted has a Denial of Service (DoS) in twisted.names via Crafted DNS Compression Pointer Chains
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | Twisted | <= 25.5.0 | 26.4.0rc2 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Twisted | Twisted | before 26.4.0 Version 26.4.0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-grgv-6hw6-v9g4
- https://github.com/twisted/twisted/security/advisories/GHSA-grgv-6hw6-v9g4
- https://github.com/twisted/twisted/commit/e11cd82bdd79b3ebbb0e8635cbb9c76df2b5af09
- https://nvd.nist.gov/vuln/detail/CVE-2026-42304
- https://github.com/pypa/advisory-database/tree/main/vulns/twisted/PYSEC-2026-160.yaml