CVE-2017-7839: Mozilla Firefox vulnerability

CVE-2017-7839: Control characters prepended before "javascript:" URLs pasted in the addressbar can cause the leading chara...

Control characters prepended before "javascript:" URLs pasted in the addressbar can cause the leading characters to be ignored and the pasted JavaScript to be executed instead of being blocked. This could be used in social engineering and self-cross-site-scripting (self-XSS) attacks where users are convinced to copy and paste text into the addressbar. This vulnerability affects Firefox < 57.

UnknownCVSS not scoredNot KEV-listedUpdatedAug 5, 2024, 16:19 UTC (UTC+00:00)

Security readout for executives and security teams

Older Firefox versions could be tricked into running pasted script text in the address bar if control characters were placed before a blocked URL scheme. This mainly enables social engineering and self-XSS: the victim must be persuaded to paste text into the address bar. The source bundle does not show active exploitation. Exposure is limited to endpoints still running Mozilla Firefox versions earlier than 57, especially unmanaged legacy desktops, kiosks, VDI images, or frozen application environments. Current Firefox deployments are not indicated as affected by the provided sources. Treat this as legacy-browser cleanup, not an emergency internet-wide incident. Prioritize if regulated workstations, shared kiosks, or unmanaged endpoints may still run Firefox before 57. Business risk is mostly phishing-assisted user compromise. Mitigation focus: Retire or upgrade any Firefox installation earlier than version 57.; Confirm current remediation against Mozilla MFSA2017-24 guidance.; Block unsupported browser versions through endpoint management where feasible..

Prepared: Jun 7, 2026, 06:44 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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Vulnerability profileCVE Program record

Severity: Unknown
CVSS: Not scored
Known Exploited: No
Published: Jun 11, 2018, 21:00 UTC (UTC+00:00)

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors

0Timeline events

0ADP providers

3Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

CVE List V5 sourceCVE List V5
https://bugzilla.mozilla.org/show_bug.cgi?id=1402896CVE reference · x_refsource_CONFIRM
https://www.mozilla.org/security/advisories/mfsa2017-24/CVE reference · x_refsource_CONFIRM

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus

MozillaFirefoxunspecifiedListed

Weakness

CWE details

No CWE listed

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