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CVE-2015-4520
Mozilla Firefox before 41.0 and Firefox ESR 38.x before 38.3 allow remote attackers to bypass CORS preflight protection mechanisms by…
- 6.4MediumCVSS base score
- 2.6%Exploitation in 30 daysEPSS · top 14% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
Mozilla Firefox before 41.0 and Firefox ESR 38.x before 38.3 allow remote attackers to bypass CORS preflight protection mechanisms by leveraging (1) duplicate cache-key generation or (2) retrieval of a value from an incorrect HTTP Access-Control-* response header.
Timeline
ID reserved
By mozilla
- 4 months later
· 4 months later
Published
- 9 years later
· 9 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 2.0 | Medium6.4 | AV:N/AC:L/Au:N/C:P/I:P/A:N |
- EPSS (exploitation in 30 days)
- 2.6% · top 14% of all CVEs (10 Nov 2026)
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.4.
Affected products
n/a
- affected n/a
References
21
- http://www.mozilla.org/security/announce/2015/mfsa2015-111.html (opens in a new tab)x_refsource_CONFIRMx_transferred
- SUSE-SU-2015:1680 (opens in a new tab)vendor-advisoryx_refsource_SUSEx_transferred
- SUSE-SU-2015:2081 (opens in a new tab)vendor-advisoryx_refsource_SUSEx_transferred
- openSUSE-SU-2015:1681 (opens in a new tab)vendor-advisoryx_refsource_SUSEx_transferred
- USN-2754-1 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
- USN-2743-4 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
- http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html (opens in a new tab)x_refsource_CONFIRMx_transferred
- http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html (opens in a new tab)x_refsource_CONFIRMx_transferred
- USN-2743-3 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
- RHSA-2015:1834 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- USN-2743-2 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
- https://bugzilla.mozilla.org/show_bug.cgi?id=1200856 (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://bugzilla.mozilla.org/show_bug.cgi?id=1200869 (opens in a new tab)x_refsource_CONFIRMx_transferred
- 1033640 (opens in a new tab)vdb-entryx_refsource_SECTRACKx_transferred
- RHSA-2015:1852 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- DSA-3365 (opens in a new tab)vendor-advisoryx_refsource_DEBIANx_transferred
- 76816 (opens in a new tab)vdb-entryx_refsource_BIDx_transferred
- SUSE-SU-2015:1703 (opens in a new tab)vendor-advisoryx_refsource_SUSEx_transferred
- openSUSE-SU-2015:1679 (opens in a new tab)vendor-advisoryx_refsource_SUSEx_transferred
- openSUSE-SU-2015:1658 (opens in a new tab)vendor-advisoryx_refsource_SUSEx_transferred
- USN-2743-1 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2015-4540 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2015-4520)Record last updated .