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CVE-2015-8973

21
FAUCET Score

CVE-2015-8973 is a high-severity access restriction bypass vulnerability affecting MyBB versions prior to 1.6.18 and 1.8.6, as well as MyBB Merge System before 1.8.6. This flaw, located in xmlhttp.php, allows remote attackers to bypass intended access controls, specifically related to forum passwords. With a CVSS score of 8.3, it presents a low-complexity attack vector that can lead to partial compromise of confidentiality, integrity, and availability. There is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
<= 1.8.5CPE matchmatch criteria
cpe:2.3:a:mybb:merge_system:*:*:*:*:*:*:*:*
<= 1.6.17CPE matchmatch criteria
cpe:2.3:a:mybb:mybb:*:*:*:*:*:*:*:*
1.8.0CPE matchmatch criteria
cpe:2.3:a:mybb:mybb:1.8.0:*:*:*:*:*:*:*
1.8.1CPE matchmatch criteria
cpe:2.3:a:mybb:mybb:1.8.1:*:*:*:*:*:*:*
1.8.2CPE matchmatch criteria
cpe:2.3:a:mybb:mybb:1.8.2:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

8.3HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
LOW
Exploitability Score
3.9
Impact Score
3.7
CvssVersion
3.0

Exploit Intelligence

EPSS Score
1.63%
Probability of exploitation in next 30 days
EPSS Percentile
73.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0163 is in the 56th percentile among its peer group of 51,506 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 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

Remediation records are not available for this CVE.

References

blog.mybb.com / 2015/09/07/mybb-1-8-6-1-6-18-merge-system-1-8-6-release
Release NotesVendor Advisory
openwall.com / lists/oss-security/2016/11/10/8
Third Party Advisory
openwall.com / lists/oss-security/2016/11/18/1
Mailing ListThird Party Advisory
securityfocus.com / bid/94397
Third Party AdvisoryVDB Entry