{"id":"CVE-2026-118513","kind":"vulnerability","aliases":["CVE-2026-118513"],"related":[],"title":"Symfony: client certificate spoofing lets attackers log in as any user","description":"Authentication bypass by spoofing in X509Authenticator and X509AuthenticationListener of Symfony versions prior to 5.4.56, 6.x prior to 6.4.50, 7.x prior to 7.4.23, and 8.x prior to 8.1.11 allows an attacker holding a certificate from the application's trusted CA who can influence the CN to authenticate as an arbitrary user of the application, including a privileged one, following an incomplete fix for CVE-2026-45063.\nX509Authenticator extracts the user identifier from the Subject DN (Distinguished Name) that the web server passes in $_SERVER['SSL_CLIENT_S_DN']. The fix for CVE-2026-45063 anchored that extraction to an RDN (Relative Distinguished Name) boundary, but the regular expression used was not escape-aware. The expression runs against an already serialized DN, so it cannot tell an RDN separator from a separator character that occurs inside a value. Under RFC 2253, used by Apache and by nginx's $ssl_client_s_dn, a comma inside a value is escaped as \\, and the expression reads it as a separator regardless. RFC 2253 also does not treat / as a separator, so it leaves it bare inside a value, while the expression treats every / as one. The legacy X509_NAME_oneline() format, used by Apache's LegacyDNStringFormat and by nginx's $ssl_client_s_dn_legacy, is the mirror image: it escapes / as \\/ and leaves , bare. In that format, a certificate with no emailAddress attribute, or whose poisoned CN precedes it, authenticates as the smuggled address.\n\n\n\n\n\nTo cover both RFC 2253 and the legacy X509_NAME_oneline() format, X509Authenticator and X509AuthenticationListener now split the DN into RDNs before looking for the attribute, instead of matching the attribute against the serialized string. They select the separator from the serialization, split on unescaped occurrences of that separator only, unescape each RDN afterwards with the rules of its format, and require the attribute to span a whole RDN. The accepted value grammar is unchanged.\n\n\n\n\nApplications that pass a per-attribute user key (such as SSL_CLIENT_S_DN_Email) and deployments whose CA generates or validates the subject are not affected by this vulnerability.","summary":"An incomplete fix in Symfony's X.509 client certificate authenticators still lets a certificate holder from the application's trusted CA put a different user's identifier into the certificate's Subject DN. The application then authenticates the attacker as that user, including a privileged one.","severity":"high","cvss":7.7,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["apache","nginx","package","php","symfony","x509-client-auth"],"not_affected_if":["ca-generated-subject","no-x509-auth","per-attribute-key"],"how_to_check":"- Search the security configuration for `x509` to see whether client certificate authentication is enabled.\n- Check the installed Symfony version in `composer.lock` against the fixed versions below.\n- Check whether the web server passes the client DN to PHP in `SSL_CLIENT_S_DN` (Apache) or `$ssl_client_s_dn` (nginx), and whether the user key is set per attribute such as `SSL_CLIENT_S_DN_Email`.","fix":"- Symfony 5.4: `5.4.56`\n- Symfony 6.4: `6.4.50`\n- Symfony 7.4: `7.4.23`\n- Symfony 8.1: `8.1.11`","status":"open","published_at":"2026-11-04T13:17:25+00:00","first_seen_at":"2026-11-04T13:27:00+00:00","triaged_at":"2026-11-04T13:28:04+00:00","updated_at":"2026-11-04T13:28:04+00:00","category":"package","confidence":0.8,"triage":{"at":"2026-11-04T13:28:04Z","model":"claude-haiku-5-5","output":{"fix":"- Symfony 5.4: `5.4.56`\n- Symfony 6.4: `6.4.50`\n- Symfony 7.4: `7.4.23`\n- Symfony 8.1: `8.1.11`","reach":"network","title":"Symfony: client certificate spoofing lets attackers log in as any user","impact":"high","summary":"An incomplete fix in Symfony's X.509 client certificate authenticators still lets a certificate holder from the application's trusted CA put a different user's identifier into the certificate's Subject DN. The application then authenticates the attacker as that user, including a privileged one.","audience":"developers","category":"package","nicknames":[],"who_cares":["symfony","php","x509-client-auth","apache","nginx"],"confidence":0.8,"fix_status":"available","needs_auth":"yes","worst_case":"attacker logs in as any user, including administrators","analyst_note":"","how_to_check":"- Search the security configuration for `x509` to see whether client certificate authentication is enabled.\n- Check the installed Symfony version in `composer.lock` against the fixed versions below.\n- Check whether the web server passes the client DN to PHP in `SSL_CLIENT_S_DN` (Apache) or `$ssl_client_s_dn` (nginx), and whether the user key is set per attribute such as `SSL_CLIENT_S_DN_Email`.","plain_action":"","needs_analyst":false,"not_affected_if":["no-x509-auth","per-attribute-key","ca-generated-subject"],"who_is_affected":"Applications that use Symfony's X509Authenticator or X509AuthenticationListener to log users in from client certificates, where the user identifier is taken from the Subject DN. Applications that set a per-attribute user key, or whose certificate authority generates or validates the subject, are not affected.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.001282,"input_tokens":4842,"output_tokens":1596,"severity_before":"high"},"analyst_status":null,"analyst_note":null,"search":"'-118513':14A,17A '-2026':13A,16A,139C,167C '-45063':140C,168C '2253':215C,245C,322C '5.4.56':86C '6':87C '6.4.50':91C '7':92C '7.4.23':96C '8':98C '8.1.11':102C 'accept':388C 'address':317C 'affect':420C 'afterward':371C 'allow':103C 'alreadi':194C 'also':246C 'anchor':169C 'apach':18B,218C,276C 'applic':44B,61B,111C,128C,393C 'arbitrari':124C 'attack':6A,65B,105C 'attribut':306C,343C,348C,381C,399C 'auth':26B 'authent':36B,63B,73C,121C,313C 'awar':188C 'bare':257C,297C 'boundari':178C 'bypass':74C 'ca':47B,114C,412C 'cannot':199C 'certif':3A,35B,40B,56B,108C,302C 'charact':207C 'client':2A,25B,34B,160C,224C,284C,405C 'cn':119C,310C 'comma':228C 'cover':319C 'cve':12A,15A,138C,166C 'deploy':410C 'differ':50B 'distinguish':150C,176C 'dn':59B,149C,162C,196C,226C,286C,336C,407C 'email':408C 'emailaddress':305C 'escap':187C,233C,293C 'escape-awar':186C 'everi':265C 'express':182C,190C,237C,263C 'extract':142C,171C 'fix':29B,136C,164C 'follow':133C 'format':273C,300C,329C,377C 'generat':413C 'grammar':390C 'hold':106C 'holder':41B 'identifi':53B,145C 'imag':291C 'includ':69B,129C 'incomplet':28B,135C 'influenc':117C 'insid':210C,229C,258C 'instead':344C 'key':401C 'leav':255C,296C 'legaci':269C,287C,325C 'legacydnstringformat':278C 'let':5A,38B 'log':7A 'look':340C 'match':346C 'mirror':290C 'name':151C,177C,271C,327C 'nginx':19B,221C,281C 'occur':209C 'occurr':363C 'one':72B,132C,267C 'onelin':272C,328C 'packag':20B 'pass':156C,395C 'per':398C 'per-attribut':397C 'php':21B 'poison':309C 'preced':311C 'prior':84C,89C,94C,100C 'privileg':71B,131C 'put':48B 'rdn':174C,202C,370C,386C 'rdns':338C 'read':238C 'regardless':243C 'regular':181C 'relat':175C 'requir':379C 'rfc':214C,244C,321C 'rule':374C 'run':191C 'select':354C 'separ':203C,206C,242C,252C,356C,366C 'serial':195C,351C,359C 'server':155C,158C 'smuggl':316C 'span':383C 'split':334C,360C 'spoof':4A,76C 'ssl':159C,223C,283C,404C 'still':37B 'string':352C 'subject':58B,148C,417C 'symfoni':1A,22B,31B,82C 'tell':200C 'treat':249C,264C 'trust':46B,113C 'unchang':392C 'unescap':362C,368C 'use':183C,216C,274C 'user':11A,51B,68B,125C,144C,400C 'valid':415C 'valu':212C,231C,260C,389C 'version':83C 'vulner':423C 'web':154C 'whole':385C 'whose':308C,411C 'x':88C,93C,99C 'x.509':33B 'x509':24B,270C,326C 'x509-client-auth':23B 'x509authenticationlistener':80C,332C 'x509authenticator':78C,141C,330C","nicknames":[],"mitigations":[],"who_affected":"Applications that use Symfony's X509Authenticator or X509AuthenticationListener to log users in from client certificates, where the user identifier is taken from the Subject DN. Applications that set a per-attribute user key, or whose certificate authority generates or validates the subject, are not affected.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"developers","plain_action":null,"pkeys":[],"ptokens":[],"labels":["apache","high","nginx","package","php","symfony","x509clientauth"],"campaign_type":null,"first_public_at":"2026-11-04T11:43:49+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/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":"596c5446-0ce5-4ba2-aa66-48b3b757a647","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-118513","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-118513","severity":null,"published_at":"2026-11-04T13:17:25+00:00","modified_at":"2026-11-04T13:17:25+00:00","first_seen_at":"2026-11-04T13:27:00+00:00","fetched_at":"2026-11-04T13:27:00+00:00","note":null}],"documents":[{"id":67051,"url":"https://github.com/symfony/symfony/commit/0f5e26b664d17cb235ca6b6d15bf4e7ac83d25cb","title":"Patch: github.com","kind":"other","source":"nvd","publisher":"vendor","text":null,"published_at":null,"relation":"fix","confidence":null,"note":"Patch: github.com"},{"id":67052,"url":"https://github.com/symfony/symfony/commit/e885d7549a234530ce1d59121d4ac3ee35b1caea","title":"Patch: github.com","kind":"other","source":"nvd","publisher":"vendor","text":null,"published_at":null,"relation":"fix","confidence":null,"note":"Patch: github.com"},{"id":67053,"url":"https://github.com/symfony/symfony/security/advisories/GHSA-5w3m-mfwg-9f8r","title":"Vendor advisory: github.com","kind":"vendor","source":"nvd","publisher":"vendor","text":null,"published_at":"2026-11-04T11:43:49+00:00","relation":"advisory","confidence":null,"note":"Vendor advisory: github.com"}],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}