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CVE-2011-3656

19
FAUCET Score

CVE-2011-3656 describes a cross-site scripting (XSS) vulnerability affecting Mozilla Firefox versions before 3.6.24 and 4.x through 7. This medium-severity flaw (CVSS 6.1) allows remote attackers to inject malicious web script or HTML through specific HTTP 0.9 error handling, non-default port usage, and content-sniffing mechanisms. Exploitation requires user interaction, but the attack complexity is low, potentially leading to limited impact on confidentiality and integrity. There is no evidence of active exploitation, public exploit code, or significant community discussion for this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
< 3.6.24CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
>= 4.0, <= 7.0CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.1MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
2.7
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.76%
Probability of exploitation in next 30 days
EPSS Percentile
51.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0076 is in the 58th percentile among its peer group of 26,221 CVEs.

Social Chatter

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

Media Mentions

No media coverage found for this CVE.

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

Remediation

Vendor Patches (8)

mozillavendor investigatingvia nvd_reference
View patch
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux 4Fixed in: firefox
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux 4Fixed in: seamonkey
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux 4Fixed in: thunderbird
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux Extended Update Support 5.7Fixed in: firefox
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux Extended Update Support 5.7Fixed in: thunderbird
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux Extended Update Support 6.1Fixed in: firefox
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux Extended Update Support 6.1Fixed in: thunderbird

Vendor Advisories (1)

redhatCVE-2011-3656Moderate

Mozilla: Possible XSS via HTTP 0.9 errors and content-sniffing

Nov 9, 2011

References

bugzilla.mozilla.org / show_bug.cgi
Issue TrackingVendor Advisory