{"id":"CVE-2026-117991","kind":"vulnerability","aliases":["CVE-2026-117991"],"related":[],"title":"Firefox: boundary error in Layout text and fonts code, fixed in 159","description":"Incorrect boundary conditions in the Layout: Text and Fonts component. This vulnerability was fixed in Firefox 159 and Firefox ESR 153.6.","summary":"Firefox's Layout: Text and Fonts component has an incorrect boundary condition, a memory-safety-style bug whose exact effect the sources do not describe. The fix shipped in Firefox 159 and Firefox ESR 153.6.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["browser","desktop","firefox","other"],"not_affected_if":["already-updated"],"how_to_check":"- Run `firefox --version` (or check About Firefox) and compare against `159` and ESR `153.6`\n- unknown whether other Firefox-based builds are affected","fix":"- Update Firefox to `159` or later\n- Update Firefox ESR to `153.6` or later","status":"open","published_at":"2026-10-27T14:16:57+00:00","first_seen_at":"2026-10-27T14:32:24+00:00","triaged_at":"2026-10-27T14:34:59+00:00","updated_at":"2026-10-27T14:34:59+00:00","category":"other","confidence":0.3,"triage":{"at":"2026-10-27T14:34:59Z","model":"claude-haiku-5-5","output":{"fix":"- Update Firefox to `159` or later\n- Update Firefox ESR to `153.6` or later","reach":"unknown","title":"Firefox: boundary error in Layout text and fonts code, fixed in 159","impact":"medium","summary":"Firefox's Layout: Text and Fonts component has an incorrect boundary condition, a memory-safety-style bug whose exact effect the sources do not describe. The fix shipped in Firefox 159 and Firefox ESR 153.6.","category":"other","nicknames":[],"who_cares":["firefox","desktop","browser"],"confidence":0.3,"needs_auth":"unknown","worst_case":"unknown; sources do not state the impact","analyst_note":"Check the Mozilla security advisory for Firefox 159 and ESR 153.6 for the bug's impact, trigger conditions, and whether it is exploitable from web content; NVD entry lacks severity and CVSS.","how_to_check":"- Run `firefox --version` (or check About Firefox) and compare against `159` and ESR `153.6`\n- unknown whether other Firefox-based builds are affected","needs_analyst":true,"not_affected_if":["already-updated"],"who_is_affected":"Anyone running Firefox or Firefox ESR older than the fixed versions, on desktop or wherever the browser is deployed. The sources do not say which page content or configurations trigger the bug, so unknown whether a default install is exposed to web content. Teams that do not run Firefox can skip it.","user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000602,"input_tokens":3254,"output_tokens":554,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-117991':15A,18A '-2026':14A,17A '153.6':57B,78C '159':12A,53B,74C 'boundari':2A,32B,59C 'browser':19B 'bug':39B 'code':9A 'compon':28B,67C 'condit':33B,60C 'cve':13A,16A 'describ':47B 'desktop':20B 'effect':42B 'error':3A 'esr':56B,77C 'exact':41B 'firefox':1A,21B,22B,52B,55B,73C,76C 'fix':10A,49B,71C 'font':8A,27B,66C 'incorrect':31B,58C 'layout':5A,24B,63C 'memori':36B 'memory-safety-styl':35B 'safeti':37B 'ship':50B 'sourc':44B 'style':38B 'text':6A,25B,64C 'vulner':69C 'whose':40B","nicknames":[],"mitigations":[],"who_affected":"Anyone running Firefox or Firefox ESR older than the fixed versions, on desktop or wherever the browser is deployed. The sources do not say which page content or configurations trigger the bug, so unknown whether a default install is exposed to web content. Teams that do not run Firefox can skip it.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-27T14:16:57+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-117991","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-117991","severity":null,"published_at":"2026-10-27T14:16:57+00:00","modified_at":"2026-10-27T14:16:57+00:00","first_seen_at":"2026-10-27T14:32:24+00:00","fetched_at":"2026-10-27T14:32:24+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}