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Vulnerability details: VCID-7rnk-nc4b-xfgt
Vulnerability ID VCID-7rnk-nc4b-xfgt
Aliases CVE-2018-18509
Summary A flaw during verification of certain S/MIME signatures causes emails to be shown in Thunderbird as having a valid digital signature, even if the shown message contents aren't covered by the signature. The flaw allows an attacker to reuse a valid S/MIME signature to craft an email message with arbitrary content.
Status Published
Exploitability 0.5
Weighted Severity 9.0
Risk 4.5
Affected and Fixed Packages Package Details
Weaknesses (2)
CWE-451 User Interface (UI) Misrepresentation of Critical Information
CWE-347 Improper Verification of Cryptographic Signature
System Score Found at
cvssv3 5.3 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2018-18509.json
epss 0.0028 https://api.first.org/data/v1/epss?cve=CVE-2018-18509
epss 0.0028 https://api.first.org/data/v1/epss?cve=CVE-2018-18509
epss 0.0028 https://api.first.org/data/v1/epss?cve=CVE-2018-18509
epss 0.0028 https://api.first.org/data/v1/epss?cve=CVE-2018-18509
epss 0.0028 https://api.first.org/data/v1/epss?cve=CVE-2018-18509
epss 0.0028 https://api.first.org/data/v1/epss?cve=CVE-2018-18509
epss 0.0028 https://api.first.org/data/v1/epss?cve=CVE-2018-18509
epss 0.0028 https://api.first.org/data/v1/epss?cve=CVE-2018-18509
epss 0.0028 https://api.first.org/data/v1/epss?cve=CVE-2018-18509
epss 0.0028 https://api.first.org/data/v1/epss?cve=CVE-2018-18509
epss 0.0028 https://api.first.org/data/v1/epss?cve=CVE-2018-18509
epss 0.0028 https://api.first.org/data/v1/epss?cve=CVE-2018-18509
epss 0.0028 https://api.first.org/data/v1/epss?cve=CVE-2018-18509
epss 0.0028 https://api.first.org/data/v1/epss?cve=CVE-2018-18509
epss 0.0028 https://api.first.org/data/v1/epss?cve=CVE-2018-18509
epss 0.0028 https://api.first.org/data/v1/epss?cve=CVE-2018-18509
epss 0.0028 https://api.first.org/data/v1/epss?cve=CVE-2018-18509
epss 0.0028 https://api.first.org/data/v1/epss?cve=CVE-2018-18509
cvssv2 5.0 https://nvd.nist.gov/vuln/detail/CVE-2018-18509
cvssv3 5.3 https://nvd.nist.gov/vuln/detail/CVE-2018-18509
archlinux Critical https://security.archlinux.org/AVG-908
generic_textual high https://www.mozilla.org/en-US/security/advisories/mfsa2019-06
Reference id Reference type URL
http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00043.html
http://packetstormsecurity.com/files/152703/Johnny-You-Are-Fired.html
https://access.redhat.com/errata/RHSA-2019:1144
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2018-18509.json
https://api.first.org/data/v1/epss?cve=CVE-2018-18509
https://bugzilla.mozilla.org/show_bug.cgi?id=1507218
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-18356
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-18500
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-18501
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-18505
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-18509
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-18512
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-18513
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-5785
http://seclists.org/fulldisclosure/2019/Apr/38
https://github.com/RUB-NDS/Johnny-You-Are-Fired
https://github.com/RUB-NDS/Johnny-You-Are-Fired/blob/master/paper/johnny-fired.pdf
https://www.mozilla.org/security/advisories/mfsa2019-06/
http://www.openwall.com/lists/oss-security/2019/04/30/4
1677613 https://bugzilla.redhat.com/show_bug.cgi?id=1677613
ASA-201902-23 https://security.archlinux.org/ASA-201902-23
AVG-908 https://security.archlinux.org/AVG-908
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
CVE-2018-18509 https://nvd.nist.gov/vuln/detail/CVE-2018-18509
mfsa2019-06 https://www.mozilla.org/en-US/security/advisories/mfsa2019-06
USN-3897-1 https://usn.ubuntu.com/3897-1/
No exploits are available.
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2018-18509.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: AV:N/AC:L/Au:N/C:N/I:P/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2018-18509
Exploitability (E) Access Vector (AV) Access Complexity (AC) Authentication (Au) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

high

functional

unproven

proof_of_concept

not_defined

local

adjacent_network

network

high

medium

low

multiple

single

none

none

partial

complete

none

partial

complete

none

partial

complete
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2018-18509
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.51044
EPSS Score 0.0028
Published At July 30, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2025-07-31T08:10:00.713733+00:00 Mozilla Importer Import https://github.com/mozilla/foundation-security-advisories/blob/master/announce/2019/mfsa2019-06.yml 37.0.0