Resource exhaustion in Twisted
CVE-2026-115778
Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.10.0rc1, twisted.conch.telnet.Telnet.dataReceived appends every byte received after IAC SB to a persistent subnegotiation buffer until IAC SE is received, without applying a maximum length. Telnet option negotiation occurs before authentication, so an unauthenticated peer can omit the terminator and continuously grow the buffer. The resulting memory exhaustion can terminate the process and every service it hosts. This issue is fixed in version 26.10.0rc1.
Vulnerability class: DoS (Denial of Service)
Published .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Twisted — versions < 26.10.0rc1
Weakness classification (CWE)
References
- github.com/twisted/twisted/security/advisories/GHSA-cwm5-jh59-mwxr
- github.com/twisted/twisted/pull/12750
- github.com/twisted/twisted/commit/073ba878c6c07d569cb61abc5ae76d46eff1b529
- github.com/twisted/twisted/commit/5d91cc66a3591faba758a80a1479e0103602facc
- github.com/twisted/twisted/releases/tag/twisted-26.10.0rc1
Frequently asked questions
- What is CVE-2026-115778?
- CVE-2026-115778 is a high-severity vulnerability in Twisted, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2026-10-23.
- How severe is CVE-2026-115778?
- High severity. CVSS v3 base score is 7.5 out of 10.