@sigstore/core has DSSE payloadType type-binding failure

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.4 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L

EPSS

• CVE-2026-48758: 0.24% estimated exploitation activity in the next 30 days; percentile 15.00 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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…

Published by the source

26 Jun 2026, 19:11 UTC

Last modified by the source

10 Sep 2026, 03:51 UTC

Source last checked

26 Oct 2026, 12:56 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-jfc7-64v2-mr8c

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-jfc7-64v2-mr8c

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-48758

Advisory: @sigstore/core has DSSE payloadType type-binding failure
IDs: CVE-2026-48758, GHSA-jfc7-64v2-mr8c
Record: https://patchnext.com/advisories/cve-2026-48758 (revision 2, source checked 26 Oct 2026, 12:56 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @sigstore/core 3.2.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @sigstore/core: affected <= 3.2.0; fixed in 3.2.1

## Suggested inspection (read-only)
- `npm ls @sigstore/core --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @sigstore/core.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-jfc7-64v2-mr8c (OSV record GHSA-jfc7-64v2-mr8c lists affected ranges: npm @sigstore/core >=0 <3.2.1 (fixed))
- Verified: https://github.com/advisories/GHSA-jfc7-64v2-mr8c (GitHub-reviewed advisory GHSA-jfc7-64v2-mr8c lists affected ranges: npm @sigstore/core >=0 <=3.2.0)

Commands are suggestions: review each one before running it.