{"id":"GHSA-crwc-vw2r-qr6m","summary":"OGNL stricter-invocation block list bypass via java.lang.reflect reflection proxies","details":"### Summary\n\nOGNL's optional *stricter invocation* mode maintains a block list that prevents expressions from directly calling methods on dangerous classes such as `Runtime`, `ProcessBuilder`, and `ClassLoader`. The block list filters on the **declaring class of the method OGNL invokes**. Because `java.lang.reflect.Method` (and `Constructor`/`Field`) are not on the list, an expression can use reflection as a proxy — `someMethod.invoke(target, args)` — to reach a blocked method. The real call (e.g. `ProcessBuilder.start()`) then executes inside the JDK reflection machinery and never passes back through OGNL's `invokeMethod`, so the block list never sees it.\n\n### Proof of concept\n\nUnder the default OGNL context (public-only access, stricter invocation enabled), the following expression creates a file even though a direct `new ProcessBuilder(...).start()` is blocked:\n\n```\n(#pb=new java.lang.ProcessBuilder({\"/usr/bin/touch\",\"rce-proof.txt\"}),\n #methods=@java.lang.ProcessBuilder@class.getMethods(),\n #names=#methods.{ #this.getName() },\n #startIdx=#names.indexOf(\"start\"),\n #methods[#startIdx].invoke(#pb, null))\n```\n\n### Impact and scope — please read carefully\n\n**This is hardening of a defense-in-depth secondary layer, not a break of OGNL's primary security boundary.**\n\nIn OGNL the stricter-invocation block list is a *secondary* mitigation. The **primary** access-control gate is the `MemberAccess` implementation supplied by the integrating framework or application, which OGNL consults on every constructor and method call. Frameworks that evaluate untrusted expressions are expected to install a restrictive `MemberAccess` — for example, Apache Struts' `SecurityMemberAccess`, which excludes dangerous classes and the `java.lang.reflect` package. Against such a `MemberAccess` this PoC is blocked at the very first step (the `new ProcessBuilder(...)` constructor), before reflection is ever reachable.\n\nThe default context that ships with OGNL intentionally allows all public members and is **not** designed to sandbox untrusted input. An application that evaluates attacker-controlled expressions with that permissive default already has many paths to code execution, and this technique is not required to achieve it.\n\n**You are affected only if all of the following hold:** (1) your application evaluates untrusted/attacker-controlled OGNL expressions, (2) it uses OGNL's default permissive `MemberAccess` (or an equivalently permissive one that allows `java.lang.reflect`), and (3) it relies on the stricter-invocation block list as its sandbox. **Properly configured consumers — including Apache Struts with its `SecurityMemberAccess` — are not affected.** The actual protection for untrusted-expression scenarios remains a correctly configured `MemberAccess`; the block list should not be treated as a sandbox.\n\n### Fix\n\n`java.lang.reflect.Method`, `java.lang.reflect.Constructor`, and `java.lang.reflect.Field` are added to the stricter-invocation block list, so reflection objects can no longer be used as invocation proxies in stricter mode. The `java.lang.invoke.MethodHandle` path was verified not to be exploitable (its signature-polymorphic `invoke`/`invokeExact` fail through OGNL's reflection-based invocation), so no additional classes are required.\n\n### Credit\n\nReported responsibly through Tidelift by 毛锐 (youyi.mr@alibaba-inc.com).","aliases":["CVE-2026-113730"],"modified":"2026-10-21T16:45:04.303510159Z","published":"2026-10-21T16:31:04Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2026-10-21T16:31:04Z","nvd_published_at":"2026-10-20T22:19:30Z","cwe_ids":["CWE-693"],"severity":"MODERATE"},"references":[{"type":"WEB","url":"https://github.com/orphan-oss/ognl/security/advisories/GHSA-crwc-vw2r-qr6m"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-113730"},{"type":"WEB","url":"https://github.com/orphan-oss/ognl/commit/16396fa4b560221294c2ab9ca04b76b161115e7d"},{"type":"WEB","url":"https://github.com/orphan-oss/ognl/commit/f4c17f794754d516ea799c36ed8524d1b7fb98e2"},{"type":"PACKAGE","url":"https://github.com/orphan-oss/ognl"},{"type":"WEB","url":"https://github.com/orphan-oss/ognl/releases/tag/OGNL_3_4_13"}],"affected":[{"package":{"name":"ognl:ognl","ecosystem":"Maven","purl":"pkg:maven/ognl/ognl"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.4.13"}]}],"versions":["2.1.4","2.2.2","2.3.2","2.4.1","2.5.1","2.6.3","2.6.5","2.6.7","2.6.9","2.7","2.7.1","2.7.2","2.7.3","3.0","3.0.1","3.0.10","3.0.11","3.0.12","3.0.13","3.0.14","3.0.15","3.0.16","3.0.17","3.0.18","3.0.19","3.0.2","3.0.20","3.0.21","3.0.3","3.0.4","3.0.5","3.0.6","3.0.6.1","3.0.6.2","3.0.7","3.0.8","3.0.9","3.1","3.1.1","3.1.10","3.1.11","3.1.12","3.1.14","3.1.15","3.1.16","3.1.17","3.1.18","3.1.19","3.1.2","3.1.20","3.1.21","3.1.22","3.1.23","3.1.24","3.1.25","3.1.26","3.1.27","3.1.28","3.1.29","3.1.3","3.1.4","3.1.5","3.1.6","3.1.7","3.1.8","3.1.9","3.2","3.2.1","3.2.10","3.2.11","3.2.12","3.2.13","3.2.14","3.2.15","3.2.16","3.2.17","3.2.18","3.2.19","3.2.2","3.2.20","3.2.21","3.2.3","3.2.4","3.2.5","3.2.6","3.2.7","3.2.8","3.2.9","3.3.0","3.3.1","3.3.2","3.3.3","3.3.4","3.3.5","3.4.0","3.4.1","3.4.10","3.4.11","3.4.12","3.4.2","3.4.3","3.4.4","3.4.5","3.4.6","3.4.7","3.4.8","3.4.9"],"database_specific":{"last_known_affected_version_range":"\u003c= 3.4.12","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-crwc-vw2r-qr6m/GHSA-crwc-vw2r-qr6m.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L"}]}