A flaw in Firefox’s Printing: Output component allows an attacker to trigger a denial‑of‑service condition that terminates the print subprocess and can render printing functionality unusable. The impact is limited to disruption of the browser’s print capability, potentially causing service outages for users who rely on printing from the browser. This vulnerability is a classic resource exhaustion issue where the attacker supplies input that forces the printing engine to crash.

Mozilla Firefox, specifically all releases prior to version 158 and all ESR releases prior to 153.5, and Mozilla Thunderbird, all releases prior to version 158 and all ESR releases prior to 153.5. Users still running any older stable or ESR build are affected and should consider updating to a patched release.

The CVSS score is 6.5, but exploit probability metrics such as EPSS are not publicly available. The vulnerability is not listed in the CISA KEV catalog, so its real‑world exploitation likelihood is currently unknown. However, the attack vector is likely remote or local through malformed print jobs; a malicious web page or local file could supply the triggering input. Until monitoring data or exploit proof‑of‑concepts appear, the risk is considered moderate but should be mitigated as a priority.