Extension "powermail": Improper Neutralization of Special Elements Used in a Template Engine
CVE-2026-77136 is a critical-severity improper neutralization of special elements used in a template engine vulnerability in Extension "powermail" from TYPO3, with a CVSS 4.0 base score of 9.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 13.2.1, 12.6.1, 10.9.3 as the first without the flaw, so updating Extension "powermail" to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 1.06% chance of exploitation within 30 days, higher than 65% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Extension "powermail" to 13.2.1 or 12.6.1 or 10.9.3, whichever matches your release line, or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| TYPO3 | Extension "powermail" | 13.0.0 up to, but not including, 13.2.1; 11.0.0 up to, but not including, 12.6.1; before 10.9.3 | 13.2.1, 12.6.1, 10.9.3 |
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.
- Attack requirements
- PresentThe target must be in a specific state or configuration for the attack to work.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Confidentiality (vulnerable system)
- HighSerious loss of confidentiality on the vulnerable system.
- Integrity (vulnerable system)
- HighSerious loss of integrity on the vulnerable system.
- Availability (vulnerable system)
- HighSerious loss of availability on the vulnerable system.
- Confidentiality (other systems)
- HighSerious loss of confidentiality on systems beyond the vulnerable one.
- Integrity (other systems)
- HighSerious loss of integrity on systems beyond the vulnerable one.
- Availability (other systems)
- HighSerious loss of availability on systems beyond the vulnerable one.
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. Scored by CNA.
Official description
The extension passes the raw value of a form field configured as "This field contains the name of the sender" directly into a Fluid View as template source, without any sanitization, and renders it. An anonymous, unauthenticated user can submit Fluid template syntax in that field to execute arbitrary Fluid ViewHelpers leading to disclosure of server configuration, environment variables and application source, and potentially remote code execution. Exploitation requires only that a form field is configured as the sender_name field, a common and default-adjacent Powermail configuration. No authentication or user interaction beyond a normal form submission is required. This vulnerability is reported to be actively exploited in the wild.
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.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
Recent Improper Neutralization of Special Elements Used in a Template Engine vulnerabilities
- 7.7 High severity
- 8.8 High severity
- 9.3 Critical severity
- 9.8 Critical severity
- 7.6 High severity
- 8.1 High severity
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