Cotonti CMS Comments Plugin PHP Object Injection via Unrestricted unserialize() in Create/Edit Actions

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-71294
StatePUBLISHED
AssignerTuranSec
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-05 13:24:54 UTC
Updated2026-08-05 16:17:08 UTC
DescriptionCotonti CMS's Comments plugin deserializes user-supplied data without restricting the classes that may be instantiated. In plugins/comments/controllers/actions/CreateAction.php, a `ci` POST parameter obtained via `cot_import('ci', 'P', 'TXT')` (trim-only sanitization) is passed to `unserialize(base64_decode($ci))` with no `allowed_classes` restriction, reachable by any member with write access to comments (the default `Auth_members => 'RW'` setting in plugins/comments/comments.setup.php). In plugins/comments/controllers/actions/EditAction.php, a `cb` parameter is similarly deserialized via `unserialize(base64_decode($this->comeback))` in prepareComeBack(), reachable by any member editing their own comment. Because unserialize() is called without allowed_classes, an attacker can construct a serialized PHP object of any class loaded by Cotonti (a PHP Object Injection primitive). This was demonstrated in practice using Cotonti's own MySQL_cache class: a crafted serialized MySQL_cache object, once deserialized and later garbage-collected, triggers its __destruct()->flush() chain, causing an attacker-controlled INSERT INTO cot_cache with attacker-chosen row values — confirming genuine POP-chain exploitation, with further impact (including potential RCE) contingent on other gadget chains available in a given Cotonti installation's loaded classes. A third sink in DeleteAction.php contains the identical unserialize() pattern but is gated behind an admin-only authorization check and is not reachable by ordinary members.

Risk And Classification

Primary CVSS: v3.1 7.6 HIGH from 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c

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

Problem Types: CWE-502 | CWE-502 CWE-502

VersionSourceTypeScoreSeverityVector
3.1309f9ea4-e3e9-4c6c-b79d-e8eb01244f2cSecondary7.6HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L
3.1CNADECLARED7.7HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
Low
Availability
Low

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Cotonti Cotonti affected * custom Not specified

References

ReferenceSourceLinkTags
github.com/Cotonti/Cotonti/blob/master/plugins/comments/controllers/acti... 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c github.com
github.com/Cotonti/Cotonti 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Saidakbarxon Maxsudxonov (en)

© CVE.report 2026

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report