How severe is CVE-2020-28017?

CVE-2020-28017 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-28017 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 36% (98th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-28017?

CVE-2020-28017 affects Exim. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-28017?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2020-28017 published?

CVE-2020-28017 was published on 2021-05-06 and last updated on 2026-06-17.

CVE-2020-28017

CVE-2020-28017 is a critical-severity vulnerability in Exim with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 36% places it in the 98th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-190.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 36% (98th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-190
Affected product: Exim
Published: 2021-05-06
Last modified: 2026-06-17

Description

Exim 4 before 4.94.2 allows Integer Overflow to Buffer Overflow in receive_add_recipient via an e-mail message with fifty million recipients. NOTE: remote exploitation may be difficult because of resource consumption.

Frequently asked questions

What is CVE-2020-28017?: Exim 4 before 4.94.2 allows Integer Overflow to Buffer Overflow in receive_add_recipient via an e-mail message with fifty million recipients. NOTE: remote exploitation may be difficult because of resource consumption.
How severe is CVE-2020-28017?: CVE-2020-28017 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-28017 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 36% (98th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-28017?: CVE-2020-28017 affects Exim. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-28017?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2020-28017 published?: CVE-2020-28017 was published on 2021-05-06 and last updated on 2026-06-17.

References

https://www.exim.org/static/doc/security/CVE-2020-qualys/CVE-2020-28017-RCPTL.txt

Affected products (1)

cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:*

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Other CWE-190 (Integer Overflow or Wraparound) vulnerabilities

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CVE-2025-64721 — Critical (CVSS 10.0): Sandboxie is a sandbox-based isolation software for 32-bit and 64-bit Windows NT-based operating systems. In versions…
CVE-2015-5108 — Critical (CVSS 10.0): Integer overflow in Adobe Reader and Acrobat 10.x before 10.1.15 and 11.x before 11.0.12, Acrobat and Acrobat Reader DC…
CVE-2015-5097 — Critical (CVSS 10.0): Integer overflow in Adobe Reader and Acrobat 10.x before 10.1.15 and 11.x before 11.0.12, Acrobat and Acrobat Reader DC…
CVE-2013-2555 — Critical (CVSS 10.0): Integer overflow in Adobe Flash Player before 10.3.183.75 and 11.x before 11.7.700.169 on Windows and Mac OS X, before…

Browse all CWE-190 (Integer Overflow or Wraparound) vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE:

76.12.128.249 (ipv4-addr)
50.116.72.139 (ipv4-addr)
166.62.41.190 (ipv4-addr)
132.148.155.138 (ipv4-addr)
50.62.22.47 (ipv4-addr)
31.131.22.122 (ipv4-addr)
193.68.57.43 (ipv4-addr)
192.169.201.223 (ipv4-addr)