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Vulnerabilities

Vulnerability · CVE-2026-115774

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

Published Oct 23, 2026 · catalog updated Oct 24, 2026 · Red Hat Red Hat Enterprise Linux

Last checked Nov 5, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-115774. EPSS is 0.52%. Act only if a listed version of Red Hat Red Hat Enterprise Linux is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Medium6.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.52%
Remediation
Advisory link
Affected products
Debian:12 twisted · Debian:13 twisted · Debian:14 twisted · pypi twisted

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Debian:12 twisted22.4.0-4, 22.4.0-4+deb12u1, 23.10.0-1
  • Debian:13 twisted24.11.0-1, 25.5.0-1, 25.5.0-2
  • Debian:14 twisted24.11.0-1, 25.5.0-1, 25.5.0-2
  • pypi twistedversion unspecified

How to fix CVE-2026-115774

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-115774. EPSS is 0.52%. Act only if a listed version of Red Hat Red Hat Enterprise Linux is installed.

Which versions are affected?

Compare what you have installed with 22.4.0-4, 22.4.0-4+deb12u1, 23.10.0-1, 24.11.0-1, 25.5.0-1, 25.5.0-2. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-835: Infinite Loop. EPSS 0.52%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Debian security

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 23, 2026 · Red Hat Security Data

    Detected

    twisted: twisted: Denial of Service via negative size in IMAP search command

  2. Oct 24, 2026 · Trivy Vulnerability DB

    Updated

    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 sy

Sources

  • CVE.orgVulnerability recordCVE-2026-115774

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-115774

    30-day exploitation probability 0.52%

    first.org
  • GitLab Advisory DatabasePackage advisoryCVE-2026-115774

    An infinite-loop vulnerability (CWE-835) in the Twisted IMAP4 server lets an authenticated client freeze the whole process with one small command. twisted.mail.imap4.parseNestedParens reads an IMAP literal size with int() and never rejects a negative value. A negative size such as {-100} drives the parser cursor negative, and because a negative Python index wraps around the end of the string inste

    advisories.gitlab.com
  • Red Hat Security DataVendor advisoryCVE-2026-115774

    twisted: twisted: Denial of Service via negative size in IMAP search command

    access.redhat.com
  • Trivy Vulnerability DBPackage advisoryDEBIAN-CVE-2026-115774

    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 sele

    osv.dev

References

Freshness

Last verified in this catalog Nov 5, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSNov 5, 2026
  • GitLab Advisory DatabaseOct 27, 2026
  • Red Hat Security DataOct 26, 2026
  • CVE.orgOct 24, 2026
  • Trivy Vulnerability DBOct 24, 2026