CVE-2026-115776 twisted CVE debrief

Who should care

Defenders who use Twisted's IRC server should assess their exposure and prioritize verifying the impact on their systems. This includes reviewing system configurations, understanding the potential operational impacts, and planning for mitigations or updates. Security teams and operators of IRC servers based on Twisted should be aware of the vulnerability and take proactive steps to verify exposure and apply fixes or compensating controls as necessary.

Why it matters

CVE-2026-115776 is a denial-of-service vulnerability in Twisted's IRC server that can be exploited by an unauthenticated remote client. Defenders should prioritize verifying exposure and assessing the impact on their systems.

• Denial of service due to memory exhaustion
• Potential disruption of IRC server services

Technical summary

The `twisted.words.protocols.irc.IRC.dataReceived` method is vulnerable to an unbounded buffer attack, which can cause a denial-of-service condition. An unauthenticated remote client can exploit this vulnerability by sending a stream of bytes without a line feed. The method appends every received byte to a per-connection buffer and only removes data at a line feed, with no maximum length. This allows an attacker to cause memory exhaustion, potentially disrupting the IRC server service. The issue is exacerbated by the fact that the IRC server inherits this method unchanged, and the buffering occurs before any authentication.

Defensive priority

Defenders should prioritize verifying exposure and assessing the impact on their systems, especially if they use Twisted's IRC server.

Recommended defensive actions

• Verify exposure by checking if the Twisted IRC server is used in the environment.
• Assess the impact on systems that use Twisted's IRC server.
• Apply the fix from the vendor, if available.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The vulnerability is caused by the unbounded buffer in the `twisted.words.protocols.irc.IRC.dataReceived` method. This method appends every received byte to a per-connection buffer and only removes data at a line feed, with no maximum length.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.