{"id":"CVE-2026-125332","aliases":["GHSA-w4xr-hqv8-ch44"],"url":"https://o3.security/vulnerability/CVE-2026-125332","summary":"Forge: TLS client crash on an unsupported ServerHello compression method","details":"### Summary\nA `forge.tls` client accepts any compression method in the ServerHello, although it only offers no compression. An unknown method makes `connection.process()` throw an uncaught `Error` when the client handles ServerHelloDone, before the server is authenticated. A malicious server or an on-path attacker can use this to terminate a Node.js process. Fixed in node-forge 1.4.3.\n\n### Details\nThe client's ClientHello offers only the `null` compression method. `tls.parseHelloMessage()` in `lib/tls.js` stores the ServerHello's `compression_method` for the client without checking it (the code has a `TODO: handle compression methods`). When the client handles ServerHelloDone it calls `tls.createConnectionState()`, which throws `Error('Unsupported compression algorithm.')` for any method other than `null` (0) and `deflate` (1). The exception propagates out of `connection.process()`.\n\nThe ServerHello isn't authenticated until the server's Finished message, so an on-path attacker can change the compression byte of a genuine ServerHello; the certificate chain still verifies. Applications that pass socket data to `process()` without catching exceptions terminate. This includes `forge.tls.wrapSocket`, which calls `process()` from its socket data handler, and `forge.http`, which uses it. A `deflate` (1) method, also never offered, makes the handshake fail later with an error instead of a crash.\n\nServers are not affected: a server always selects no compression.\n\nThe fix fails the handshake with an `illegal_parameter` alert, through the connection's `error` callback, when the ServerHello selects any compression method other than `null`.\n\n#### Patches\nFixed in node-forge 1.4.3.\n\n#### Workarounds\nCatch exceptions thrown by `connection.process()` and close the socket.\n\n#### Resources\n- RFC 5246, section 7.4.1.3 (Server Hello): https://www.rfc-editor.org/rfc/rfc5246#section-7.4.1.3\n- Related: GHSA-525v-9gp9-w22h (another TLS client crash during the handshake, fixed in 1.4.1): https://github.com/digitalbazaar/forge/security/advisories/GHSA-525v-9gp9-w22h\n\n#### Severity\nCVSS 3.1: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H (5.9, Moderate)\nCVSS 4.0 (informational): CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N (8.2)\nCVSS 4.0 has no counterpart to 3.1's AC:H beyond AT:P and scores this higher; the severity rating follows CVSS 3.1.\n\n#### Credits\nReported by @alienkeric.\n\n### Proof of concept\nA server (or on-path attacker) sends a ServerHello with `compression_method` 0xff, followed by a valid Certificate and ServerHelloDone:\n\n    client.handshake();\n    client.process(serverHello + certificate + serverHelloDone);\n    // <= 1.4.2: throws Error: Unsupported compression algorithm.\n    // 1.4.3: error callback with \"Unsupported compression method.\"\n\nThe reporter's PoC (a CA-issued server certificate and the default verify callback) is in tests/pocs/ghsa-w4xr-hqv8-ch44.js, and regression tests are in tests/unit/tls.js.\n\n### Impact\nApplications that use `forge.tls` as a client (directly, through `forge.tls.wrapSocket`, or through `forge.http`) and pass data from a network socket to `connection.process()` are affected. The server they connect to, or an on-path attacker, can make `process()` throw before the server is authenticated; if the application doesn't catch it, the Node.js process terminates, dropping all its connections. Servers built on `forge.tls` are not affected. There is no confidentiality or integrity impact.","published":"2026-11-10T18:47:10.884Z","modified":"2026-11-12T02:48:31.648049244Z","cvss":{"score":5.9,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"npm","name":"node-forge","fixedVersion":"1.4.3"}],"fix":{"url":"https://github.com/digitalbazaar/forge/commit/1d9816d333c23c523ef2bd8b24282c87db2654ef","label":"digitalbazaar/forge@1d9816d"},"references":[{"type":"WEB","url":"https://github.com/digitalbazaar/forge/releases/tag/v1.4.3"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/125xxx/CVE-2026-125332.json"},{"type":"ADVISORY","url":"https://github.com/digitalbazaar/forge/security/advisories/GHSA-w4xr-hqv8-ch44"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-125332"},{"type":"FIX","url":"https://github.com/digitalbazaar/forge/commit/1d9816d333c23c523ef2bd8b24282c87db2654ef"},{"type":"FIX","url":"https://github.com/digitalbazaar/forge/pull/1169"},{"type":"PACKAGE","url":"https://github.com/digitalbazaar/forge"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-11-12T02:48:31.648049244Z"}}