{"id":"CVE-2026-117906","kind":"vulnerability","aliases":["CVE-2026-117906"],"related":[],"title":"Firefox: use-after-free in CSS parsing lets attacker-controlled pages crash or run code","description":"Use-after-free in the CSS Parsing and Computation component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, and Firefox ESR 153.6.","summary":"A use-after-free bug in Firefox's CSS parsing and computation component reuses memory after it has been freed. Mozilla fixed it in Firefox 159 and Firefox ESR 115.44 and 153.6, and the sources do not say what an attacker can do beyond that.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["browsers","desktop","firefox","runtime"],"not_affected_if":["unknown"],"how_to_check":"- Run `firefox --version` (or check About Firefox) and compare against `159` or the ESR builds `115.44` and `153.6`.\n- Check the version on managed machines with your fleet or MDM tool.","fix":"- Update Firefox to `159` or later.\n- Update Firefox ESR to `115.44` or `153.6`, depending on which ESR branch is in use.","status":"open","published_at":"2026-10-27T14:16:46+00:00","first_seen_at":"2026-10-27T14:32:22+00:00","triaged_at":"2026-10-27T14:37:33+00:00","updated_at":"2026-10-27T14:37:33+00:00","category":"runtime","confidence":0.5,"triage":{"at":"2026-10-27T14:37:33Z","model":"claude-haiku-5-5","output":{"fix":"- Update Firefox to `159` or later.\n- Update Firefox ESR to `115.44` or `153.6`, depending on which ESR branch is in use.","reach":"internet","title":"Firefox: use-after-free in CSS parsing lets attacker-controlled pages crash or run code","impact":"high","summary":"A use-after-free bug in Firefox's CSS parsing and computation component reuses memory after it has been freed. Mozilla fixed it in Firefox 159 and Firefox ESR 115.44 and 153.6, and the sources do not say what an attacker can do beyond that.","category":"runtime","nicknames":[],"who_cares":["firefox","browsers","desktop"],"confidence":0.5,"needs_auth":"no","worst_case":"unknown; a browser memory corruption flaw may allow crashes or code execution","analyst_note":"Confirm the exploitability and impact of the CSS use-after-free in the Mozilla security advisory for Firefox 159 and ESR 115.44/153.6 (https://nvd.nist.gov/vuln/detail/CVE-2026-117906).","how_to_check":"- Run `firefox --version` (or check About Firefox) and compare against `159` or the ESR builds `115.44` and `153.6`.\n- Check the version on managed machines with your fleet or MDM tool.","needs_analyst":true,"not_affected_if":["unknown"],"who_is_affected":"Anyone running a Firefox build older than 159 or an ESR build older than 115.44 or 153.6 is exposed, most likely by opening a web page that triggers the CSS code path. Servers and build pipelines that do not run a browser are unlikely to be affected. The sources do not say whether the flaw is reachable without user interaction.","user_interaction":"yes","needs_special_setup":"no","severity_if_unknown":"unknown"},"cost_usd":0.000645,"input_tokens":3256,"output_tokens":638,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-117906':20A,23A '-2026':19A,22A '115.44':58B,93C '153.6':60B,97C '159':54B,90C 'attack':11A,69B 'attacker-control':10A 'beyond':72B 'browser':24B 'bug':33B 'code':17A 'compon':41B,83C 'comput':40B,82C 'control':12A 'crash':14A 'css':7A,37B,79C 'cve':18A,21A 'desktop':25B 'esr':57B,92C,96C 'firefox':1A,26B,35B,53B,56B,89C,91C,95C 'fix':50B,87C 'free':5A,32B,76C 'freed':48B 'let':9A 'memori':43B 'mozilla':49B 'page':13A 'pars':8A,38B,80C 'reus':42B 'run':16A 'runtim':27B 'say':66B 'sourc':63B 'use':3A,30B,74C 'use-after-fre':2A,29B,73C 'vulner':85C","nicknames":[],"mitigations":[],"who_affected":"Anyone running a Firefox build older than 159 or an ESR build older than 115.44 or 153.6 is exposed, most likely by opening a web page that triggers the CSS code path. Servers and build pipelines that do not run a browser are unlikely to be affected. The sources do not say whether the flaw is reachable without user interaction.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-27T14:16:46+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-117906","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-117906","severity":null,"published_at":"2026-10-27T14:16:46+00:00","modified_at":"2026-10-27T14:16:46+00:00","first_seen_at":"2026-10-27T14:32:22+00:00","fetched_at":"2026-10-27T14:32:22+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"}