Stack overflow when parsing deeply nested input in pest_grammars

Exploitation

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

CVSS

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

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Impact In affected versions, parsing deeply nested input with `pest_grammars::json::JsonParser` can exhaust the native stack and abort the hosting process. Applications that accept attacker-controlled JSON without suitable resource limits may therefore be vulnerable to denial of service. The reported reproduction demonstrates this behavior with deeply nested JSON arrays. The nesting required to trigger an overflow depends on the platform, available stack space, and build configuration; there is no portable safe nesting threshold.

Patches Upgrade to `pest_grammars` 2.9.3 or later. Version 2.9.3 requires the updated `pest` runtime and includes regression tests for deeply nested JSON with the optional call budget disabled. Supported std builds automatically check available native stack headroom at parser checkpoints and return a handled stack limit reached error when insufficient space is detected. This protection operates independently of `pest::set_call_limit()`. See the 2.9.3…

Published by the source

16 Oct 2026, 12:00 UTC

Last modified by the source

16 Oct 2026, 23:30 UTC

Source last checked

23 Oct 2026, 22:04 UTC

1. Revision 1 · created · 24 Oct 2026

   Published from osv record RUSTSEC-2026-0366

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# Patch Next advisory brief: GHSA-7632-4q2x-hvjw

Advisory: Stack overflow when parsing deeply nested input in pest_grammars
IDs: GHSA-7632-4q2x-hvjw
Record: https://patchnext.com/advisories/rustsec-2026-0366 (revision 1, source checked 23 Oct 2026, 22:04 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 3.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: pest_grammars 2.9.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io pest_grammars: affected >= 0.0.0-0, < 2.9.3; fixed in 2.9.3

## Suggested inspection (read-only)
- crates.io pest_grammars: check the installed version with your package manager.

## 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 pest_grammars.
- 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/RUSTSEC-2026-0366 (OSV record RUSTSEC-2026-0366 lists affected ranges: crates.io pest_grammars >=0.0.0-0 <2.9.3 (fixed))

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