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CVE-2026-46644— symfony/polyfill-intl-idn accepts xn-- labels whose Punycode payload decodes to ASCII-only: insecure equivalence

Quick assessment

Affected
symfony polyfill
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Symfony polyfill是Symfony组织的一款提供功能兼容补全的代码包。 Symfony polyfill 1.17.1版本至1.38.1之前版本存在输入验证错误漏洞，该漏洞源于输入验证错误，Idn::process()未强制执行UTS #46修订版33要求解码的ACE标签至少包含一个非ASCII代码点，导致接受Punycode有效载荷为空或解码为仅ASCII代码点的xn--标签，从而使原本不同的域名被视为相等，可能导致使用polyfill规范化或比较主机名的应用程序中出现黑名单绕过、URL解

AI Predicted 5.4 Difficulty: Easy EPSS 0.54% · P44

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 2

VendorProduct Version RangeStatus
symfony polyfill >= 1.17.1, < 1.38.1 affected
symfony polyfill-intl-idn >= 1.17.1, < 1.38.1 affected
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I. Basic Information for CVE-2026-46644

Vulnerability Information
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Vulnerability Title
symfony/polyfill-intl-idn accepts xn-- labels whose Punycode payload decodes to ASCII-only: insecure equivalence
Source: CVE Program / CVE List V5
Vulnerability Description
Symfony Polyfill backports PHP features and provides compatibility layers for extensions and functions. From 1.17.1 until 1.38.1, symfony/polyfill-intl-idn accepts xn-- labels whose Punycode payload is empty or decodes to ASCII-only code points because Idn::process() does not enforce the UTS #46 revision 33 requirement that decoded ACE labels contain at least one non-ASCII code point. Originally unequal domain names can be regarded as equal, which can lead to blacklist bypassing, inconsistent URL parsing, and server-side request forgery in applications using the polyfill to canonicalise or compare hostnames. This issue is fixed in version 1.38.1.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
CWE-1289
Source: CVE Program / CVE List V5
Vulnerability Title
Symfony polyfill 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Symfony polyfill是Symfony组织的一款提供功能兼容补全的代码包。 Symfony polyfill 1.17.1版本至1.38.1之前版本存在输入验证错误漏洞，该漏洞源于输入验证错误，Idn::process()未强制执行UTS #46修订版33要求解码的ACE标签至少包含一个非ASCII代码点，导致接受Punycode有效载荷为空或解码为仅ASCII代码点的xn--标签，从而使原本不同的域名被视为相等，可能导致使用polyfill规范化或比较主机名的应用程序中出现黑名单绕过、URL解
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
symfony polyfill >= 1.17.1, < 1.38.1 -
symfony polyfill-intl-idn >= 1.17.1, < 1.38.1 -

II. Public POCs for CVE-2026-46644

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III. Intelligence Information for CVE-2026-46644

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Patches & Fixes for CVE-2026-46644 (1)

Vendor Advisories for CVE-2026-46644 (1)

Vendor Pages for CVE-2026-46644 (1)

Same Patch Batch · symfony · 2026-07-14 · 30 CVEs total

CVE-2026-45133 Symfony: [Yaml] Harden the parser when handling untrusted input
CVE-2026-48761 Symfony: HtmlSanitizer UrlAttributeSanitizer Misses URL Attributes on <object>, <applet>,
CVE-2026-48736 Symfony: IpUtils::PRIVATE_SUBNETS Omits IPv6 Transition Forms (6to4, NAT64, Teredo, IPv4-c
CVE-2026-48747 Symfony: Mailomat Mailer Webhook Parser Reads the HMAC Algorithm from the Request: Signatu
CVE-2026-48760 Symfony: HtmlSanitizer URL Parser Deny Gates Underinclusive: Percent-Encoded BiDi Marks an
CVE-2026-48489 Symfony: Security Firewall Bypass via failure_forward Subrequest: Unauthenticated Access t
CVE-2026-48784 Symfony: UrlGenerator Dot-Segment Encoding Skips Every Other Chained `../` or `./` → Gener
CVE-2026-47212 Symfony: Twilio Notifier Webhook Parser Never Verifies the X-Twilio-Signature HMAC: Unauth
CVE-2026-45068 Symfony: Argument Injection in SendmailTransport via Dash-Prefixed Recipient Address
CVE-2026-45071 Symfony: XXE (Local File Disclosure) in DomCrawler::addXmlContent() via validateOnParse =
CVE-2026-47767 Symfony: SymfonyRuntime CVE-2024-50340 Patch Bypass: Web Requests Can Still Set APP_ENV/AP
CVE-2026-45075 Symfony: HEAD Request Bypasses methods: ['GET'] Filter in #[IsGranted] / #[IsSignatureVali
CVE-2026-45304 Symfony: YAML Parser Exponential Memory Allocation via Recursive Collection-Alias Expansio
CVE-2026-45063 Symfony: Identity Spoofing via Unanchored DN Regex in X509Authenticator
CVE-2026-45070 Symfony: Email Header Injection via Non-Token Characters in Mime Parameter Names
CVE-2026-45756 Symfony: JsonPath Evaluates Attacker-Controlled Regular Expressions in match()/search() Wi
CVE-2026-45754 Symfony: Mailjet Mailer Webhook Parser Never Verifies the Configured Secret — Unauthentica
CVE-2026-45069 Symfony: OidcTokenHandler Accepts JWTs Missing aud/iss/exp Claims
CVE-2026-45753 Symfony: HtmlSanitizer UrlAttributeSanitizer Omits action/formaction/poster/cite — javascr
CVE-2026-45072 Symfony: Stored XSS in WebProfiler CodeExtension::fileExcerpt() — Unescaped Non-PHP File R

Showing top 20 of 30 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same vendor: symfony
Same weakness: CWE-1289

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