CVE-2020-28013

Local privilege escalation via parse_fix_phrase overflow

Published May 6, 2021 · Updated Aug 4, 2024

Heap-based buffer overflow in Exim 4 before 4.94.2 allows local users to gain root privileges via crafted command-line input. The parse_fix_phrase() routine passes a negative length from the -F '.(' option to strncpy(), causing writes beyond the heap destination buffer. Exploitation requires local command-line execution of Exim and can provide root-level privileges; the advisory does not establish remote reachability for this flaw.

CVSS severity7.8
High
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in Exim 4 before 4.94.2 allows local users to gain root privileges via crafted command-line input. The parse_fix_phrase() routine passes a negative length from the -F '.(' option to strncpy(), causing writes beyond the heap destination buffer. Exploitation requires local command-line execution of Exim and can provide root-level privileges; the advisory does not establish remote reachability for this flaw.

The record

CVE
CVE-2020-28013
Published
May 6, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 6, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.2NVDAV:L/AC:L/Au:N/C:C/I:C/A:C
7.8NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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