Description
Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.10.0rc1, twisted.words.protocols.irc.IRC.dataReceived retains all bytes received without a line feed in its per-connection buffer and applies no maximum line length. The twisted.words.service.IRCUser server subclass inherits this behavior, and buffering occurs before PASS, NICK, or USER authentication commands. An unauthenticated connection can continuously grow the buffer until the shared server process runs out of memory and drops all users. This issue is fixed in version 26.10.0rc1.
Published: 2026-10-23
Score: 7.5 High
EPSS: n/a
KEV: No
Impact: Remote Denial of Service (RDoS)
Action: Apply Patch
AI Analysis

Impact

Twisted’s IRC server implementation buffers all incoming bytes without a line feed and imposes no maximum line length before authentication, allowing an unauthenticated client to send an arbitrarily long sequence of data that will grow the per-connection buffer until the process runs out of memory and terminates all active users. The flaw results in a denial of service whereby the entire server becomes unavailable until it is restarted.

Affected Systems

All Twisted installations that include the IRC protocol module twisted.words.protocols.irc.IRC and its subclass twisted.words.service.IRCUser, specifically any version prior to Twisted 26.10.0rc1.

Risk and Exploitability

The CVSS score of 7.5 indicates a high severity of this vulnerability, and the EPSS score is not available, but the flaw can be exercised remotely without authentication by simply establishing a TCP connection to the IRC port and sending data that never contains a newline. Because it is not listed in the CISA KEV catalog, no widespread exploitation data is known, yet the unbounded buffer makes it a useful target for attackers seeking to crash the service with minimal effort.

Generated by OpenCVE AI on October 23, 2026 at 21:50 UTC.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Upgrade to Twisted 26.10.0rc1 or later, which limits line length and prevents the buffer from growing unchecked.
  • Restrict network access to the IRC port to trusted IPs or implement firewall rules to limit unwanted connections.
  • Monitor memory usage on the Twisted server and set up alerts for abnormal memory consumption that could indicate a buffer overflow attempt.

Generated by OpenCVE AI on October 23, 2026 at 21:50 UTC.

Tracking

Sign in to view the affected projects.

Advisories
Source ID Title
Github GHSA Github GHSA GHSA-53xc-49m8-p798 Twisted: Unauthenticated Remote Denial of Service in the Twisted IRC Server via an Unbounded Line Buffer
History

Sat, 24 Oct 2026 00:30:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 threat_severity

Important

Fri, 23 Oct 2026 23:00:00 +0000

Type Values Removed Values Added
First Time appeared Twisted
Twisted twisted
Vendors & Products Twisted
Twisted twisted

Fri, 23 Oct 2026 20:30:00 +0000

Type Values Removed Values Added
Description Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.10.0rc1, twisted.words.protocols.irc.IRC.dataReceived retains all bytes received without a line feed in its per-connection buffer and applies no maximum line length. The twisted.words.service.IRCUser server subclass inherits this behavior, and buffering occurs before PASS, NICK, or USER authentication commands. An unauthenticated connection can continuously grow the buffer until the shared server process runs out of memory and drops all users. This issue is fixed in version 26.10.0rc1.
Title Twisted: Unauthenticated Remote Denial of Service in the Twisted IRC Server via an Unbounded Line Buffer
Weaknesses CWE-400
CWE-770
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Subscriptions

Twisted Twisted
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-23T20:18:38.342Z

Reserved: 2026-10-23T13:28:51.847Z

Link: CVE-2026-115776

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-23T21:17:23.180

Modified: 2026-10-23T21:17:23.180

Link: CVE-2026-115776

cve-icon Redhat

Severity : Important

Publid Date: 2026-10-23T20:18:38Z

Links: CVE-2026-115776 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-10-23T22:45:14Z

Weaknesses
  • CWE-400

    Uncontrolled Resource Consumption

  • CWE-770

    Allocation of Resources Without Limits or Throttling