Ref# ADV2026_218 | Date: Apr 8th 2026

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Mozilla published a security advisory highlighting vulnerabilities in the following products on April 7th, 2026. It is recommended that you take the necessary precautions by ensuring your products are always updated. 

• Firefox – versions prior to 149.0.2 

• Firefox ESR – versions prior to 34.1 

• Firefox ESR – versions prior to 9.1 

For more information on these updates, you can follow these URLs: 

• Security Vulnerabilities fixed in Firefox ESR 140.9.1 

• Security Vulnerabilities fixed in Firefox ESR 115.34.1 

• Security Vulnerabilities fixed in Firefox 149.0.2 

• Mozilla Security Advisories 

 

The Guyana National CIRT recommends that users and administrators review these updates and apply them where necessary. 

PDF Download:  Mozilla Security Advisory

References 

• Mozilla Security Advisory (April 7th, 2026). Retrieved from Mozilla. https://www.mozilla.org/en-US/security/advisories/mfsa2026-27/ 

 

• Mozilla Security Advisory. (April 7th, 2026). Retrieved from Canadian Centre for Cyber Security. https://www.cyber.gc.ca/en/alerts-advisories/mozilla-security-advisory-av26-323