{"id":"CVE-2026-117880","kind":"vulnerability","aliases":["CVE-2026-117880"],"related":[],"title":"Firefox: use-after-free in XML component may let attackers run code","description":"Use-after-free in the XML component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, and Firefox ESR 153.6.","summary":"A use-after-free bug in the XML component of Firefox was fixed in Firefox 159 and Firefox ESR 115.44 and 153.6. The sources do not say what an attacker gains beyond the memory corruption that a use-after-free implies.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["desktop-browsers","firefox","runtime"],"not_affected_if":["already-on-fixed-version"],"how_to_check":"- Check the installed Firefox version in the browser's About page or with `firefox --version`, and compare it against the fixed releases.\n- Check the ESR version in use, which should be `115.44` or later on the 115 branch or `153.6` or later on the 153 branch.","fix":"- Update Firefox to `159` or later, or Firefox ESR to `115.44` or `153.6` or later.","status":"open","published_at":"2026-10-27T14:16:43+00:00","first_seen_at":"2026-10-27T14:32:21+00:00","triaged_at":"2026-10-27T14:39:06+00:00","updated_at":"2026-10-27T14:39:06+00:00","category":"runtime","confidence":0.5,"triage":{"at":"2026-10-27T14:39:06Z","model":"claude-haiku-5-5","output":{"fix":"- Update Firefox to `159` or later, or Firefox ESR to `115.44` or `153.6` or later.","reach":"unknown","title":"Firefox: use-after-free in XML component may let attackers run code","impact":"high","summary":"A use-after-free bug in the XML component of Firefox was fixed in Firefox 159 and Firefox ESR 115.44 and 153.6. The sources do not say what an attacker gains beyond the memory corruption that a use-after-free implies.","category":"runtime","nicknames":[],"who_cares":["firefox","desktop-browsers"],"confidence":0.5,"needs_auth":"unknown","worst_case":"unknown; use-after-free can corrupt memory and may allow code execution","analyst_note":"Check Mozilla's security advisory for the trigger conditions, whether it is exploitable from web content, and the CVSS score.","how_to_check":"- Check the installed Firefox version in the browser's About page or with `firefox --version`, and compare it against the fixed releases.\n- Check the ESR version in use, which should be `115.44` or later on the 115 branch or `153.6` or later on the 153 branch.","needs_analyst":true,"not_affected_if":["already-on-fixed-version"],"who_is_affected":"Anyone running Firefox or Firefox ESR older than the fixed versions is in scope. The sources do not describe the conditions that trigger the bug, such as whether a malicious web page is enough or whether any XML feature must be used, so unknown.","user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000601,"input_tokens":3238,"output_tokens":555,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-117880':16A,19A '-2026':15A,18A '115.44':45B,85C '153.6':47B,89C '159':41B,82C 'attack':11A,55B 'beyond':57B 'browser':22B 'bug':30B 'code':13A 'compon':8A,34B,75C 'corrupt':60B 'cve':14A,17A 'desktop':21B 'desktop-brows':20B 'esr':44B,84C,88C 'firefox':1A,23B,36B,40B,43B,81C,83C,87C 'fix':38B,79C 'free':5A,29B,66B,71C 'gain':56B 'impli':67B 'let':10A 'may':9A 'memori':59B 'run':12A 'runtim':24B 'say':52B 'sourc':49B 'use':3A,27B,64B,69C 'use-after-fre':2A,26B,63B,68C 'vulner':77C 'xml':7A,33B,74C","nicknames":[],"mitigations":[],"who_affected":"Anyone running Firefox or Firefox ESR older than the fixed versions is in scope. The sources do not describe the conditions that trigger the bug, such as whether a malicious web page is enough or whether any XML feature must be used, so unknown.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-27T14:16:43+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-117880","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-117880","severity":null,"published_at":"2026-10-27T14:16:43+00:00","modified_at":"2026-10-27T14:16:43+00:00","first_seen_at":"2026-10-27T14:32:21+00:00","fetched_at":"2026-10-27T14:32:21+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"}