CVE-2020-28020
Exim 4 before 4.92 allows Integer Overflow to Buffer Overflow, in which an unauthenticated remote attacker can execute arbitrary code by leveraging the mishandling of continuation lines during header-length restriction.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (7.94%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
Exim 4 before 4.92 allows Integer Overflow to Buffer Overflow, in which an unauthenticated remote attacker can execute arbitrary code by leveraging the mishandling of continuation lines during header-length restriction.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 7.94% probability · 95th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-190
- Affected
- exim/exim
- Source
- cve@mitre.org
EPSS 7.9% since 26 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- http://www.openwall.com/lists/oss-security/2021/07/25/1Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/08/03/1Mailing List, Third Party Advisory
- https://www.exim.org/static/doc/security/CVE-2020-qualys/CVE-2020-28020-HSIZE.txtPatch, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/07/25/1Mailing List, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2021/08/03/1Mailing List, Third Party Advisory
- https://www.exim.org/static/doc/security/CVE-2020-qualys/CVE-2020-28020-HSIZE.txtPatch, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.