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Weekly Signal
Live intelligence Updated 20 Aug 2026 · 23:29 UTC

Exim · Exim

CVE-2026-66141

Exim before 4.99.5 allows .forward privilege escalation because force_command for a pipe transport is mishandled.

Recommended action

Handle this through the normal risk-based patching cycle while monitoring for change.

View response plan
CVSS7.8
EPSS0.1%
KEVNo
ExploitationNone
RemediationNo guidance located

Assessment

Why it matters

EPSS is 0.1%; technical severity is CVSS 7.8.

Exim before 4.99.5 allows .forward privilege escalation because force_command for a pipe transport is mishandled.

Who should care

  • Teams operating Exim
  • Vulnerability and exposure management teams
  • Security operations teams monitoring exploitation activity

Response plan

What I would do

  1. Confirm whether Exim is present in the environment.
  2. Identify affected versions and establish whether vulnerable services are exposed or reachable.
  3. Review vendor guidance and identify the supported fix or mitigation.
  4. Review relevant security telemetry for evidence of attempted or successful exploitation.
  5. Document the remediation decision and track it to verified completion.

Treatment intelligence

Remediation intelligence

No guidance located

Vendor sources are listed before government and third-party guidance. Confirm product applicability and change prerequisites before deployment.

Verification noteNo explicit patch, upgrade, mitigation or workaround is currently recorded.

Technical details

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE
CWE-829
Affected versions
Exim Exim (End Excluding 4.99.5)
Fixed versions
Exim Exim (Fixed from 4.99.5)
Published
24 July 2026
Attack vector
Local
Privileges required
Low
User interaction
None

Signal timeline

  1. CVE published
  2. Latest EPSS score: 0.1%
  3. Signal calculated at 11

External references

Live public intelligence This assessment combines public-source evidence. Validate the affected product, version and exposure against your own environment before making a risk decision.