{"id":"CVE-2026-116878","kind":"vulnerability","aliases":["CVE-2026-116878"],"related":[],"title":"Semantic MediaWiki: anonymous requests can exhaust server CPU, memory, and database connections","description":"Semantic MediaWiki from 2.5.0 before 7.3.1 contains an uncontrolled resource consumption vulnerability that allows anonymous attackers to force quadratic computation by supplying a zero limit to Special:PropertyLabelSimilarity. Attackers can send repeated requests with limit=0 to bypass the SQL LIMIT and trigger pairwise similar_text() comparisons, exhausting PHP CPU, memory, and database connections.","summary":"Semantic MediaWiki versions from 2.5.0 before 7.3.1 let anonymous visitors send requests to Special:PropertyLabelSimilarity with limit=0, which removes the SQL limit and forces quadratic string comparisons. Repeated requests can exhaust PHP CPU, memory and database connections, making the wiki unavailable.","severity":"high","cvss":8.7,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["mediawiki","package","php","self-hosted","semantic-mediawiki"],"not_affected_if":["private-wiki-login-required","version-7.3.1-or-later"],"how_to_check":"- Check the installed Semantic MediaWiki version in the wiki's Special:Version page or in composer.lock for `mediawiki/semantic-media-wiki`\n- Confirm whether Special:PropertyLabelSimilarity is reachable without login on the public wiki","fix":"- Upgrade Semantic MediaWiki to `7.3.1` or later\n- Until upgraded, restrict access to Special:PropertyLabelSimilarity at the web server or with MediaWiki access rules (unknown whether the sources list a specific workaround)","status":"open","published_at":"2026-10-27T11:17:29+00:00","first_seen_at":"2026-10-27T11:31:27+00:00","triaged_at":"2026-10-27T11:31:37+00:00","updated_at":"2026-10-27T11:31:37+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-10-27T11:31:37Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade Semantic MediaWiki to `7.3.1` or later\n- Until upgraded, restrict access to Special:PropertyLabelSimilarity at the web server or with MediaWiki access rules (unknown whether the sources list a specific workaround)","reach":"internet","title":"Semantic MediaWiki: anonymous requests can exhaust server CPU, memory, and database connections","impact":"medium","summary":"Semantic MediaWiki versions from 2.5.0 before 7.3.1 let anonymous visitors send requests to Special:PropertyLabelSimilarity with limit=0, which removes the SQL limit and forces quadratic string comparisons. Repeated requests can exhaust PHP CPU, memory and database connections, making the wiki unavailable.","category":"package","nicknames":[],"who_cares":["mediawiki","semantic-mediawiki","self-hosted","php"],"confidence":0.7,"needs_auth":"no","worst_case":"anonymous requests exhaust server CPU, memory and database connections","analyst_note":"","how_to_check":"- Check the installed Semantic MediaWiki version in the wiki's Special:Version page or in composer.lock for `mediawiki/semantic-media-wiki`\n- Confirm whether Special:PropertyLabelSimilarity is reachable without login on the public wiki","needs_analyst":false,"not_affected_if":["version-7.3.1-or-later","private-wiki-login-required"],"who_is_affected":"Sites running Semantic MediaWiki from 2.5.0 up to but not including 7.3.1 are exposed, and the exposure is greatest on public wikis where anonymous users can reach Special:PropertyLabelSimilarity. Private wikis that require login before any page is served are less exposed, though the sources do not state this explicitly. Sites already on 7.3.1 or later are not affected.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.00068,"input_tokens":3384,"output_tokens":683,"severity_before":"high"},"analyst_status":null,"analyst_note":null,"search":"'-116878':15A,18A '-2026':14A,17A '0':45B,105C '2.5.0':32B,73C '7.3.1':34B,75C 'allow':83C 'anonym':3A,36B,84C 'attack':85C,98C 'bypass':107C 'comparison':55B,116C 'comput':89C 'connect':12A,65B,123C 'consumpt':80C 'contain':76C 'cpu':8A,61B,119C 'cve':13A,16A 'databas':11A,64B,122C 'exhaust':6A,59B,117C 'forc':52B,87C 'host':24B 'let':35B 'limit':44B,50B,94C,104C,110C 'make':66B 'mediawiki':2A,19B,27B,29B,71C 'memori':9A,62B,120C 'packag':20B 'pairwis':113C 'php':21B,60B,118C 'propertylabelsimilar':42B,97C 'quadrat':53B,88C 'remov':47B 'repeat':56B,101C 'request':4A,39B,57B,102C 'resourc':79C 'self':23B 'self-host':22B 'semant':1A,26B,28B,70C 'semantic-mediawiki':25B 'send':38B,100C 'server':7A 'similar':114C 'special':41B,96C 'sql':49B,109C 'string':54B 'suppli':91C 'text':115C 'trigger':112C 'unavail':69B 'uncontrol':78C 'version':30B 'visitor':37B 'vulner':81C 'wiki':68B 'zero':93C","nicknames":[],"mitigations":[],"who_affected":"Sites running Semantic MediaWiki from 2.5.0 up to but not including 7.3.1 are exposed, and the exposure is greatest on public wikis where anonymous users can reach Special:PropertyLabelSimilarity. Private wikis that require login before any page is served are less exposed, though the sources do not state this explicitly. Sites already on 7.3.1 or later are not affected.","tier":"B","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-27T11:17:29+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","cvss_by":"disclosure@vulncheck.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-116878","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-116878","severity":null,"published_at":"2026-10-27T11:17:29+00:00","modified_at":"2026-10-27T11:17:29+00:00","first_seen_at":"2026-10-27T11:31:27+00:00","fetched_at":"2026-10-27T11:31:27+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"}