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CVE-2026-115774 · GHSA-2qrf-pqgx-qh9v

Twisted: Denial of Service in the Twisted IMAP4 Server via a Negative Literal Size in SEARCH

Risk score
44/100
CVSS
4.9 v3.1
Exploit chance (30 days)
0.6%
Published
23 Oct 2026

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What to know

What it is
Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.10.0rc1, twisted.mail.imap4.IMAP4Server reaches twisted.mail.imap4.parseNestedParens with a negative literal size in an authenticated SEARCH command after the client enters the selected mailbox state. The negative size m…
Affected
Twisted (pip) <= 26.4.0
Fix
Upgrade Twisted to 26.10.0rc1 or later.
Exploitation
No known exploitation

Story map

Story map: TwistedTHE FLAWSTHE FIXCVE-2026-115774Denial of Service in theTwisted IMAP4 Server via aNegative Literal Size in…CVSS 4.9 · EPSS 1%CVE-2026-115775Unauthenticated Remote Denialof Service in the Twistedwords domish XML Element…CVSS 8.7 · EPSS 1%CVE-2026-115776Unauthenticated Remote Denialof Service in the Twisted IRCServer via an Unbounded Line…CVSS 7.5 · EPSS 1%CVE-2026-115778Unauthenticated Remote Denialof Service in the Twisted conchTelnet Transport via an…CVSS 7.5 · EPSS 1%Upgrade Twisted26.10.0or later on your release lineWho is exposed{'products': ['Twisted'],'packages': ['Twisted'],'versions': ['<= 26.4.0']}AMBER · PATCH THIS WEEKTwistedTwisted has a vulnerability in itsXML parser that allows anunauthenticated remote peer tocause a denial of service bycontinuously adding childelements to an in-memory tree,exhausting server memory and…Where it standsNo known exploitationCONNECTS TOSame weaknessDenial of service (CWE-400)250 other warnings in 30 days →
Story map: the flaws, the fix, how it unfolded and what it connects to. Boxes link to the record or article.

At a glance

Twisted: Amber, patch this week. Twisted has a vulnerability in its XML parser that allows an unauthenticated remote peer to cause a denial of service by continuously adding child elements to an in-memory tree, exhausting server memory and terminating the process.

The flaws

  • CVE-2026-115774: Denial of Service in the Twisted IMAP4 Server via a Negative Literal Size in SEARCH (CVSS 4.9 · EPSS 1%)
  • CVE-2026-115775: Unauthenticated Remote Denial of Service in the Twisted words domish XML Element Stream via an Unbounded Element Tree (CVSS 8.7 · EPSS 1%)
  • CVE-2026-115776: Unauthenticated Remote Denial of Service in the Twisted IRC Server via an Unbounded Line Buffer (CVSS 7.5 · EPSS 1%)
  • CVE-2026-115778: Unauthenticated Remote Denial of Service in the Twisted conch Telnet Transport via an Unbounded Subnegotiation Buffer (CVSS 7.5 · EPSS 1%)

The fix

Upgrade Twisted: 26.10.0 or later on your release line

Who is exposed: {'products': ['Twisted'], 'packages': ['Twisted'], 'versions': ['<= 26.4.0']}

Where it stands

  • No known exploitation

Connects to

Why it is Yellow

  • CVSS 4.9 medium
  • On your watchlist: PyPI

Affected packages

PackageEcosystemVulnerableFixed in
Twistedpip<= 26.4.026.10.0rc1

References

Original description

Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.10.0rc1, twisted.mail.imap4.IMAP4Server reaches twisted.mail.imap4.parseNestedParens with a negative literal size in an authenticated SEARCH command after the client enters the selected mailbox state. The negative size moves the parser cursor below zero, and Python's negative indexing prevents the synchronous scanning loop from terminating. The loop freezes the single-threaded reactor, stopping other IMAP connections and any SMTP or POP3 services hosted in the same process until restart. This issue is fixed in version 26.10.0rc1.

Last activity 23 Oct 2026. Patch Forecast updates every hour.