CVE-2017-7789 — If a server sends two Strict-Transport-Security (STS) headers for a single conne

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.

01What is this vulnerability?

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.

02Affected products

Vendor	Product	Versions
Mozilla	Firefox	unspecified

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2018-06-11T21:00:00.000Z
• Last modified: 2024-08-05T16:12:28.364Z

09References

• www.securityfocus.com — http://www.securityfocus.com/bid/100374
• www.mozilla.org — https://www.mozilla.org/security/advisories/mfsa2017-18/
• bugzilla.mozilla.org — https://bugzilla.mozilla.org/show_bug.cgi?id=1074642
• www.securitytracker.com — http://www.securitytracker.com/id/1039124