Scriban: Built-in operations bypass LoopLimit and delay cancellation, enabling Denial of Service

Exploitation

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

CVSS

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

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary Scriban's LoopLimit only applies to script loop statements, not to expensive iteration performed inside operators and builtins. An attacker can submit a single expression such as {{ 1..1000000 | array.size }} and force large amounts of CPU work even when LoopLimit is set to a very small value. Details The relevant code path is: - ScriptBlockStatement.Evaluate() calls context.CheckAbort() once per statement in src/Scriban/Syntax/Statements/ScriptBlockStatement.cs lines 41–46. - LoopLimit enforcement is tied to script loop execution via TemplateContext.StepLoop(), not to internal helper iteration. - array.size in src/Scriban/Functions/ArrayFunctions.cs lines 596–609 calls list.Cast<object().Count() for non-collection enumerables. - 1..N creates a ScriptRange from ScriptBinaryExpression.RangeInclude() in src/Scriban/Syntax/Expressions/ScriptBinaryExpression.cs lines 745–748. - ScriptRange then yields every element one by one without going through StepLoop() in…

Published by the source

24 Mar 2026, 22:13 UTC

Last modified by the source

6 Jul 2026, 13:03 UTC

Source last checked

26 Oct 2026, 17:05 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-c875-h985-hvrc

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# Patch Next advisory brief: GHSA-c875-h985-hvrc

Advisory: Scriban: Built-in operations bypass LoopLimit and delay cancellation, enabling Denial of Service
IDs: GHSA-c875-h985-hvrc
Record: https://patchnext.com/advisories/ghsa-c875-h985-hvrc (revision 1, source checked 26 Oct 2026, 17:05 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: scriban.signed 7.0.0; scriban 7.0.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet scriban.signed: affected < 7.0.0; fixed in 7.0.0
- NuGet scriban: affected < 7.0.0; fixed in 7.0.0

## Suggested inspection (read-only)
- NuGet scriban.signed: check the installed version with your package manager.
- NuGet scriban: 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 scriban.signed, scriban.
- 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://github.com/advisories/GHSA-c875-h985-hvrc (GitHub-reviewed advisory GHSA-c875-h985-hvrc lists affected ranges: NuGet scriban >=0 =0 <7.0.0)

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