CyberSecBulletin
CVE-2026-71291NVD status: Deferred

core: Improper Neutralization of Special Elements Used in a Template Engine

Published Updated By the CyberSecBulletin desk

CVE-2026-71291 is a high-severity improper neutralization of special elements used in a template engine vulnerability in core from Bolt, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected core versions: 6.1 and earlier. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.55% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of core you run against the affected versions below, and install the vendor's latest release.

Affected products and versions

VendorProductAffected versionsFixed in
Boltcore6.1 and earlierNot stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.

Official description

Bolt CMS renders content field values through Twig's full application-level Environment with no SandboxExtension registered anywhere in the codebase. In src/Entity/Field.php, getTwigValue calls shouldBeRenderedAsTwig, which gates rendering only on the field definition's allow_twig flag and a regex checking for , , or ; when true, the raw field value is compiled and rendered via with no sandboxing.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Neutralization of Special Elements Used in a Template Engine

The product uses a template engine to insert or process externally-influenced input, but it does not neutralize or incorrectly neutralizes special elements or syntax that can be interpreted as template expressions or other code directives when processed by the engine.

How developers prevent this class of flaw

  • Choose a template engine that offers a sandbox or restricted mode, or at least limits the power of any available expressions, function calls, or commands.
  • Use the template engine's sandbox or restricted mode, if available.

More Improper Neutralization of Special Elements Used in a Template Engine vulnerabilities (CWE-1336)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Improper Neutralization of Special Elements Used in a Template Engine vulnerabilities

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