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MEDIUM

CVE-2026-27857

CVE-2026-27857 Vulnerability Analysis & Exploit Intelligence

Sending "NOOP (((...)))" command with 4000 parenthesis open+close results in ~1MB extra memory usage. Longer commands will result in client disconnection. This 1 MB can be left allocated for longer time periods by not sending the command ending LF. So attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. Attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. Install fixed version, there is no other remediation. No publicly available exploits are known.

Published Updated Sources: cvelistV5, OX

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Unreported

no source claims exploitation

EPSS

1%

chance of exploitation in 30 days

Affects

open xchange

18 products listed

CVSS base

4.3

MEDIUM

CISA SSVC assessment

Three decision points CISA publishes for the CVEs it assesses · SSVC 2.0.3. A stakeholder decision, not a severity score.

CISA

Exploitation

None

none · proof-of-concept · active

Automatable

No

can an attacker script all four kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Affected scope

The catalog records vendors and products as separate lists, not pairs, so which product belongs to which vendor is not something this page can say.

Products (18)

ox dovecot prored hat enterprise linux 10red hat enterprise linux 10 0 extended update supportred hat enterprise linux 7 extended lifecycle supportred hat enterprise linux 8red hat enterprise linux 8 4 advanced mission critical update supportred hat enterprise linux 8 4 extended update support long life add onred hat enterprise linux 8 6 advanced mission critical update supportred hat enterprise linux 8 6 telecommunications update servicered hat enterprise linux 8 6 update services for sap solutionsred hat enterprise linux 8 8 telecommunications update servicered hat enterprise linux 8 8 update services for sap solutionsred hat enterprise linux 9red hat enterprise linux 9 0 update services for sap solutionsred hat enterprise linux 9 2 update services for sap solutionsred hat enterprise linux 9 4 extended update supportred hat enterprise linux 9 6 extended update supportred hat enterprise linux 6

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactSource
4.3CVSS 3.1MEDIUM——cvelistV5

Weakness & attack patterns

  • CWE-400
  • CWE-770

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

  • T1499Endpoint Denial of Service
  • T1498.001Network Denial of Service: Direct Network Flood
  • T1499.003Endpoint Denial of Service: Application Exhaustion Flood

References

18 on the record

Elsewhere on this site

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.