Skip to content
Fencer Vulns
medium 5.9

CVE-2017-17689 json

The S/MIME specification allows a Cipher Block Chaining (CBC) malleability-gadget attack that can indirectly lead to plaintext exfiltration…

published 2018-05-16 8 y ago modified 2026-06-17 4 mo ago also EUVD-2017-8846

cvss
5.9
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
4.1%
EPSS 4.1% chance of exploitation in 30 days, percentile 90%
public exploits
0
none known

Summary

The S/MIME specification allows a Cipher Block Chaining (CBC) malleability-gadget attack that can indirectly lead to plaintext exfiltration, aka EFAIL.

Patch / fix

  • kf5-messagelib Debian 12 4:18.08.1-1

debian advisories DEBIAN-CVE-2017-17689

  • thunderbird Ubuntu 14.04 LTS 1:52.8.0+build1-0ubuntu0.14.04.1
  • thunderbird Ubuntu 16.04 LTS 1:52.8.0+build1-0ubuntu0.16.04.1
  • thunderbird Ubuntu 18.04 LTS 1:52.8.0+build1-0ubuntu0.18.04.1
  • kmail Ubuntu Pro 18.04 LTS 4:17.12.3-0ubuntu1+esm1
  • kdepim Ubuntu Pro 14.04 LTS 4:4.13.3-0ubuntu0.2+esm1
  • kdepim Ubuntu Pro 16.04 LTS 4:15.12.3-0ubuntu1.1+esm1
  • kf5-messagelib Ubuntu Pro 18.04 LTS 4:17.12.3-0ubuntu3+esm1

ubuntu advisories UBUNTU-CVE-2017-17689

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • enigmail openSUSE Tumbleweed 2.2.4-1.4
  • enigmail Package Hub 12 2.0.4-9.1

opensuse advisories openSUSE-SU-2024:10736-1openSUSE-SU-2018:1329-1openSUSE-SU-2018:1330-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2017-17689 updated cvss 5.3

S/MIME: CBC gadget attacks allows to exfiltrate plaintext out of encrypted emails

  • Red Hat Enterprise Linux 6 kdepim, kdepim-libs Red Hat Enterprise Linux 7 kdepim, kdepim-libs
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Enterprise Linux 6 thunderbird Red Hat Enterprise Linux 7 thunderbird Red Hat Enterprise Linux 8 thunderbird
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

4.14% chance of exploitation in the next 30 days, higher than 90% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • efail.de https://efail.de referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.0 5.9 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:P/I:N/A:N

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.