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CLEANSTART-2026-BS35481 — Security fix for CVE-2026-48758 applied in: pulumi 3.248.0-r0, renovate 44.31.0-r2, renovate 44.32.4-r1, renovate 44.32…

2026-10-03T05:25:47.649483+00:00

Affected: CleanStart: pulumi, CleanStart: renovate

CVE-2026-48758 affects multiple packages. This issue is resolved in later releases. See references for individual vulnerability details.

EUVD-2026-337879

2026-10-03T05:25:47.649541+00:00

EUVD-2026-337879

fkie_cve-2026-48758

2026-10-03T05:25:47.649557+00:00

sigstore-js provides JavaScript libraries for interacting with Sigstore services. Prior to 3.2.1, the preAuthEncoding function in @sigstore/core uses Node.js ascii encoding when converting the PAE string to bytes, allowing payloadType to be mutated after signing without invalidating the signature and breaking the type-binding guarantee that DSSE is designed to provide. This issue is fixed in version 3.2.1.

GHSA-jfc7-64v2-mr8c — @sigstore/core has DSSE payloadType type-binding failure

2026-10-03T05:25:47.649581+00:00

Affected: npm: @sigstore/core

### Impact The `preAuthEncoding` function in `@sigstore/core` uses Node.js `'ascii'` encoding when converting the PAE (Pre-Authentication Encoding) string to bytes. This allows `payloadType` to be mutated after signing without invalidating the signature, breaking the type-binding guarantee that DSSE is designed to provide.

In `packages/core/src/dsse.ts`, the PAE function builds a string containing `payloadType` and then encodes it with `Buffer.from(prefix, 'ascii')`.

In Node.js, `'ascii'` encoding for string-to-Buffer is equivalent to `'latin1'`, which **truncates characters above U+00FF to their low byte**. This means for any ASCII character, there exist Unicode characters (at U+01xx, U+02xx, etc.) that produce the identical encoded byte:

| Original | Codepoint | Mutant | Codepoint | Encoded byte | |----------|-----------|--------|-----------|--------------| | `t` | U+0074 | `Ŵ` | U+0174 | `0x74` | | `e` | U+0065 | `ť` | U+0165 | `0x65` |

An attacker can substitute every character in `payloadType` with a Unicode variant whose low byte matches, producing **identical PAE bytes** and a passing signature verification.

Additionally, `payloadType.length` returns the JavaScript string length (UTF-16 code units) rather than the UTF-8 byte length required by the DSSE spec, though this is only a contributing factor for non-ASCII types.

#### Reproduction

```javascript const { preAuthEncoding } = require('@sigstore/core/dist/dsse.js'); con…