Scriban: array.insert_at index parameter DoS bypasses LoopLimit and LimitToString

Exploitation

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

CVSS 4.0

8.7 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N · score source

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary ArrayFunctions.InsertAt in Scriban allocates index - list.Count null entries in a tight C

for loop with no bound on index. The function is exposed to template authors as array.insertat, and the fill loop ignores every existing safety control: LoopLimit, LimitToString, ObjectRecursionLimit, and RecursiveLimit. A single template such as {{ [1] | array.insertat 200000000 'x' | array.size }} causes OutOfMemoryException in well under a second on a host with 1 GB of memory, even when LoopLimit is set to 10 and LimitToString is set to 100. Because OutOfMemoryException is generally not caught by the template renderer or by typical host applications, the vulnerability terminates the host process, not just the template. This is a sibling vector to GHSA-xw6w-9jjh-p9cr / GHSA-c875-h985-hvrc / GHSA-v66j-x4hw-fv9g, which patched comparable unbounded primitives in string int, array.size, array.join, string.padleft, and string.padright. The 7.0.0 hardening pass (dde661d "Apply LoopLimit to…

Published by the source

19 May 2026, 14:35 UTC

Last modified by the source

29 Jun 2026, 15:43 UTC

Source last checked

26 Oct 2026, 17:04 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-24c8-4792-22hx

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# Patch Next advisory brief: GHSA-24c8-4792-22hx

Advisory: Scriban: array.insert_at index parameter DoS bypasses LoopLimit and LimitToString
IDs: GHSA-24c8-4792-22hx
Record: https://patchnext.com/advisories/ghsa-24c8-4792-22hx (revision 1, source checked 26 Oct 2026, 17:04 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: scriban.signed 7.2.0; scriban 7.2.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet scriban.signed: affected <= 7.1.0; fixed in 7.2.0
- NuGet scriban: affected <= 7.1.0; fixed in 7.2.0

## 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-24c8-4792-22hx (GitHub-reviewed advisory GHSA-24c8-4792-22hx lists affected ranges: NuGet scriban >=0 =0 <=7.1.0)

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