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CVE-2017-7789
If a server sends two Strict-Transport-Security (STS) headers for a single connection, they will be rejected as invalid and HTTP Strict…
Medium5.3EPSS 1.7%
- Published
- Updated
- Reserved
- Assigned by
- mozilla
Description
If a server sends two Strict-Transport-Security (STS) headers for a single connection, they will be rejected as invalid and HTTP Strict Transport Security (HSTS) will not be enabled for the connection. This vulnerability affects Firefox < 55.
Timeline
ID reserved
By mozilla
- 14 months later
· 14 months later
Published
- 6 years later
· 6 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 | 3.0 | Medium5.3 | CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N |
- EPSS (exploitation in 30 days)
- 1.7% · top 22% of all CVEs (8 Nov 2026)
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.3.
Weakness
- Failure to enable HSTS when two STS headers are sent for a connection
Affected products
References (4)
- 100374 (opens in a new tab)vdb-entryx_refsource_BIDx_transferred
- https://www.mozilla.org/security/advisories/mfsa2017-18/ (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://bugzilla.mozilla.org/show_bug.cgi?id=1074642 (opens in a new tab)x_refsource_CONFIRMx_transferred
- 1039124 (opens in a new tab)vdb-entryx_refsource_SECTRACKx_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)
- 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-2017-7789)Record last updated .