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CVE-2020-15656

24
FAUCET Score

CVE-2020-15656 describes a moderate severity vulnerability in Firefox, Firefox ESR, and Thunderbird where JIT optimizations related to the Javascript arguments object could lead to confusion in subsequent optimizations. This flaw, rated 8.8 HIGH on CVSS, could allow an unauthenticated attacker to achieve high impact on confidentiality, integrity, and availability through a low-complexity attack requiring user interaction. Despite its high CVSS score, the risk was mitigated by existing code precautions, and there is currently no evidence of active exploitation, publicly available exploit code, or significant community discussion.

Impacted Technologies

VendorProductVersion(s)CPE
< 79.0CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
< 78.1CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*
< 78.1CPE matchmatch criteria
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
15.2CPE matchmatch criteria
cpe:2.3:o:opensuse:leap:15.2:*:*:*:*:*:*:*
16.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.8HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.51%
Probability of exploitation in next 30 days
EPSS Percentile
71.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0151 is in the 71st percentile among its peer group of 14,875 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.2 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.1 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (7)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.0 Update Services for SAP SolutionsFixed in: firefox-0:78.2.0-3.el8_0
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: firefox-0:78.3.0-1.el7_9
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: firefox-0:78.2.0-2.el8_2
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8.1 Extended Update SupportFixed in: firefox-0:78.2.0-3.el8_1
View patch
mozillavendor investigatingvia nvd_reference
View patch
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: thunderbird
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: thunderbird

Vendor Advisories (1)

redhatCVE-2020-15656Moderate

Mozilla: Type confusion for special arguments in IonMonkey

Jul 28, 2020

References

lists.opensuse.org / opensuse-security-announce/2020-08/msg00025.html
Third Party Advisory
bugzilla.mozilla.org / show_bug.cgi
Issue TrackingPermissions RequiredVendor Advisory
usn.ubuntu.com / 4443-1
Third Party Advisory
mozilla.org / security/advisories/mfsa2020-30
Vendor Advisory
mozilla.org / security/advisories/mfsa2020-32
Vendor Advisory
mozilla.org / security/advisories/mfsa2020-33
Vendor Advisory