{"id":"CVE-2026-117899","kind":"vulnerability","aliases":["CVE-2026-117899"],"related":[],"title":"Firefox: use-after-free in HTTP networking can be triggered by crafted content","description":"Use-after-free in the Networking: HTTP 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 HTTP networking component reuses memory after it has been freed. The sources do not say what an attacker gets from it, beyond that it was fixed in Firefox 159, Firefox ESR 115.44 and Firefox ESR 153.6.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["desktop","firefox","managed-fleets","runtime"],"not_affected_if":["already-on-fixed-version"],"how_to_check":"- Run `firefox --version` or open Help > About Firefox and compare with `159`, `115.44` or `153.6`.\n- Check the installed ESR branch version on managed Firefox deployments.","fix":"- Update Firefox to `159` or later.\n- Update Firefox ESR to `115.44` or `153.6`, depending on the branch in use.","status":"open","published_at":"2026-10-27T14:16:45+00:00","first_seen_at":"2026-10-27T14:32:22+00:00","triaged_at":"2026-10-27T14:37:39+00:00","updated_at":"2026-10-27T14:37:39+00:00","category":"runtime","confidence":0.3,"triage":{"at":"2026-10-27T14:37:39Z","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 the branch in use.","reach":"unknown","title":"Firefox: use-after-free in HTTP networking can be triggered by crafted content","impact":"high","summary":"A use-after-free bug in Firefox's HTTP networking component reuses memory after it has been freed. The sources do not say what an attacker gets from it, beyond that it was fixed in Firefox 159, Firefox ESR 115.44 and Firefox ESR 153.6.","category":"runtime","nicknames":[],"who_cares":["firefox","desktop","managed-fleets"],"confidence":0.3,"needs_auth":"unknown","worst_case":"unknown; memory corruption in the browser's networking code","analyst_note":"Check the NVD entry and Mozilla's security advisory for the attack vector, privileges required and whether it is exploitable from web content.","how_to_check":"- Run `firefox --version` or open Help > About Firefox and compare with `159`, `115.44` or `153.6`.\n- Check the installed ESR branch version on managed Firefox deployments.","needs_analyst":true,"not_affected_if":["already-on-fixed-version"],"who_is_affected":"Anyone running Firefox or Firefox ESR builds older than the fixed versions on desktops or in managed fleets. The sources do not describe a server-side or web-app exposure, so teams that only run Firefox on end-user machines are the ones to check. unknown whether the bug needs a specific page or request pattern to trigger.","user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000618,"input_tokens":3250,"output_tokens":586,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-117899':17A,20A '-2026':16A,19A '115.44':67B,90C '153.6':71B,94C '159':64B,87C 'attack':53B 'beyond':57B 'bug':32B 'compon':38B,80C 'content':14A 'craft':13A 'cve':15A,18A 'desktop':21B 'esr':66B,70B,89C,93C 'firefox':1A,22B,34B,63B,65B,69B,86C,88C,92C 'fix':61B,84C 'fleet':25B 'free':5A,31B,75C 'freed':45B 'get':54B 'http':7A,36B,79C 'manag':24B 'managed-fleet':23B 'memori':40B 'network':8A,37B,78C 'reus':39B 'runtim':26B 'say':50B 'sourc':47B 'trigger':11A 'use':3A,29B,73C 'use-after-fre':2A,28B,72C 'vulner':82C","nicknames":[],"mitigations":[],"who_affected":"Anyone running Firefox or Firefox ESR builds older than the fixed versions on desktops or in managed fleets. The sources do not describe a server-side or web-app exposure, so teams that only run Firefox on end-user machines are the ones to check. unknown whether the bug needs a specific page or request pattern to trigger.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-27T14:16:45+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-117899","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-117899","severity":null,"published_at":"2026-10-27T14:16:45+00:00","modified_at":"2026-10-27T14:16:45+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"}