Skip to content
brandefense.io
Request A Demo
Vulnerability Intelligence

CVE-2017-16944

HighPublic exploit

The receive_msg function in receive.c in the SMTP daemon in Exim 4.88 and 4.89 allows remote attackers to cause a denial of service (infinite loop and stack exhaustion) via vectors involving BDAT commands and an improper check for a '.' character signifying the end of the…

Published May 5, 2021 · Updated Aug 4, 2026 · Also known as DEBIAN-CVE-2017-16944, UBUNTU-CVE-2017-16944

Key Facts

Patch immediately
  • CVE-2017-16944 is a high-severity vulnerability (CVSS 7.5 v3.1) affecting Exim, Debian Linux, exim4 (debian) and 9 more products.
  • It is not listed in any known-exploited vulnerabilities catalog. Public exploit code is available.
  • EPSS estimates a 63% probability of exploitation in the next 30 days.
  • Fixed versions are available, including Exim 4.89-4.17.amzn1, Exim 4.89.1-1, Exim 4.89.1-r0.
  • Brandefense priority: patch immediately, because it is very likely to be exploited soon.

CVSS v3.1

7.5

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS (30-day exploit likelihood)

63%

Higher than 99.2% of all scored CVEs

Exploited in the wild

No known

Not in a known-exploited catalog

Public exploit code

Available

Proof-of-concept or weaponized module

Get the full CVE-2017-16944 brief as a PDF

Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.

Description

The receive_msg function in receive.c in the SMTP daemon in Exim 4.88 and 4.89 allows remote attackers to cause a denial of service (infinite loop and stack exhaustion) via vectors involving BDAT commands and an improper check for a '.' character signifying the end of the content, related to the bdat_getc function.

Affected Products

57 affected entries in total
ProductAffected versionsFixed in
EximExim4.88, 4.894.89.1-1
Debian LinuxDebian9.0n/a
exim4debianSee advisory4.89-13
exim-greylistamazonSee advisory4.89-4.17.amzn1
exim-monamazonSee advisory4.89-4.17.amzn1
7 more affected products in the full CVE brief

Patched Releases

Exim

4.89-4.17.amzn1, 4.89.1-1, 4.89.1-r0, 4.94.2-4.2, 4.94.2-bp151.2.4.1, 4.94.2-bp152.6.4.1, 4.94.2-lp152.8.3.1

exim-greylist

4.89-4.17.amzn1

exim-mon

4.89-4.17.amzn1

exim-mysql

4.89-4.17.amzn1

exim-pgsql

4.89-4.17.amzn1

exim4

4.89-13, 4.89-2+deb9u2

eximon

4.94.2-4.2, 4.94.2-bp151.2.4.1, 4.94.2-bp152.6.4.1, 4.94.2-lp152.8.3.1

eximstats-html

4.94.2-4.2, 4.94.2-bp151.2.4.1, 4.94.2-bp152.6.4.1, 4.94.2-lp152.8.3.1

libspf2-2

1.2.10-bp151.4.1, 1.2.10-bp152.5.1

libspf2-devel

1.2.10-bp151.4.1, 1.2.10-bp152.5.1

libspf2-tools

1.2.10-bp151.4.1, 1.2.10-bp152.5.1

Timeline

  1. Publicly disclosed

    May 5, 2021

  2. Last updated

    Aug 4, 2026

Weakness Type

  • CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop')

References

15 more references in the full CVE brief

FAQ

Common Questions.

Is CVE-2017-16944 Running On Your Attack Surface?

Brandefense maps vulnerabilities like this one to your internet-facing assets and tells you exactly where to patch.

Request A Demo