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CVE Record

CVE-2020-28011: Exim 4 before 4.94.2 allows Heap-based Buffer Overflow in queue_run via two sender options: -R and -S.

Exim 4 before 4.94.2 allows Heap-based Buffer Overflow in queue_run via two sender options: -R and -S. This may cause privilege escalation from exim to root.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2020-28011 is a heap buffer overflow in Exim mail server versions before 4.94.2. The published description says it can allow privilege escalation from the Exim service account to root. Business urgency is highest for internet mail servers or multi-user systems still running older Exim builds.

Executive priority

Treat this as a high-priority remediation item for legacy Exim systems because the stated impact includes escalation to root. Prioritize mail servers with external exposure, shared-user access, or delayed patch cycles. Do not claim active exploitation from the supplied evidence.

Technical view

The issue is in Exim's queue_run handling of two sender options, -R and -S. The CVE describes a heap-based buffer overflow before version 4.94.2, with possible escalation from exim to root. The bundle does not include CVSS, CWE, distribution-specific impact, or detailed configuration preconditions.

Likely exposure

Exposure is limited to systems running Exim before 4.94.2. Risk is most relevant on mail infrastructure where Exim queue processing is enabled and local or mail-processing contexts can reach the vulnerable option handling. The sources do not identify affected operating-system packages or appliance products.

Exploitation context

The CVE is not listed in KEV in the provided bundle, and no cited source states active exploitation. The public description indicates privilege escalation potential, but the provided evidence does not establish remote exploitability, exploit maturity, or required access level.

Researcher notes

The supplied evidence is sparse. It identifies the vulnerable component, version boundary, and affected option handling, but not exact attack prerequisites. Researchers should consult the linked Exim/Qualys advisory and vendor package advisories before assessing reachability or exploitability in a specific environment.

Mitigation direction

  • Upgrade Exim to 4.94.2 or later where supported.
  • Check vendor or distribution advisories for backported fixes.
  • Inventory externally exposed and internal mail servers running Exim.
  • Restrict local shell access on mail servers where possible.
  • Review vendor guidance before applying configuration-only mitigations.

Validation and detection

  • Confirm the installed Exim version on all mail hosts.
  • Check package changelogs for CVE-2020-28011 backports.
  • Verify queue-run functionality after patching.
  • Review asset inventory for unmanaged Exim installations.
  • Document any systems that cannot be upgraded immediately.
Prepared
Confidence
medium
Sources
3

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

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

description · low confidence lookup

Privilege behavior lookup

The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2020-28011 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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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
2Source 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.