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CVE Record

CVE-2021-38371: The STARTTLS feature in Exim through 4.94.2 allows response injection (buffering) during MTA SMTP sending.

The STARTTLS feature in Exim through 4.94.2 allows response injection (buffering) during MTA SMTP sending.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2021-38371 is an Exim mail-server STARTTLS issue. Public sources state Exim through 4.94.2 can allow response injection during outbound SMTP sending. The bundle does not provide a CVSS score, confirmed exploitation, or detailed impact. Treat affected mail infrastructure as requiring vendor-guided review and patch planning.

Executive priority

Prioritize this for mail infrastructure governance, but do not classify it as emergency from the provided evidence alone. The main business concern is potentially affected email transport security on older Exim deployments without clear exploit-status evidence in the bundle.

Technical view

The vulnerability is described as response injection or buffering in Exim's STARTTLS feature during MTA SMTP sending, affecting Exim through 4.94.2. The provided sources do not include CWE classification, CVSS vector, exploit prerequisites, or a named fixed version beyond vendor and Debian advisory references.

Likely exposure

Exposure is most likely on systems running Exim through 4.94.2, especially mail transfer agents that send SMTP using STARTTLS. The source bundle does not identify CPEs, deployment patterns, or whether specific distributions are affected beyond a Debian LTS advisory reference.

Exploitation context

The source bundle does not show CISA KEV listing or cited evidence of active exploitation. Public disclosure and vendor documentation exist, but attacker prerequisites and practical exploitability are not detailed in the provided material.

Researcher notes

Key gaps are severity, CVSS, CWE, exploit prerequisites, and exact fixed version. Analysis should stay anchored to Exim through 4.94.2 and the STARTTLS SMTP-sending response-injection description unless vendor documentation adds more detail.

Mitigation direction

  • Inventory Exim installations and identify versions through 4.94.2.
  • Review the Exim security notice for CVE-2021-38371.
  • Check distribution advisories, including Debian LTS, for patched packages.
  • Apply vendor or distribution updates where available.
  • Avoid inventing STARTTLS workarounds without vendor guidance.

Validation and detection

  • Confirm Exim package versions on all mail relays.
  • Verify whether outbound SMTP paths use STARTTLS.
  • Map affected hosts to vendor or distribution advisory coverage.
  • Confirm patched package deployment through configuration management records.
  • Monitor vendor advisories for any updated remediation guidance.
Prepared
Confidence
medium
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2021-38371 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
5Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.