CVE-2021-27850
Detail
Modified After Enrichment
This CVE record has been updated after NVD enrichment efforts were completed. Enrichment data supplied by the NVD may require amendment due to these changes.
Description
A critical unauthenticated remote code execution vulnerability was found all recent versions of Apache Tapestry. The affected versions include 5.4.5, 5.5.0, 5.6.2 and 5.7.0. The vulnerability I have found is a bypass of the fix for CVE-2019-0195. Recap: Before the fix of CVE-2019-0195 it was possible to download arbitrary class files from the classpath by providing a crafted asset file URL. An attacker was able to download the file `AppModule.class` by requesting the URL `http://localhost:8080/assets/something/services/AppModule.class` which contains a HMAC secret key. The fix for that bug was a blacklist filter that checks if the URL ends with `.class`, `.properties` or `.xml`. Bypass: Unfortunately, the blacklist solution can simply be bypassed by appending a `/` at the end of the URL: `http://localhost:8080/assets/something/services/AppModule.class/` The slash is stripped after the blacklist check and the file `AppModule.class` is loaded into the response. This class usually contains the HMAC secret key which is used to sign serialized Java objects. With the knowledge of that key an attacker can sign a Java gadget chain that leads to RCE (e.g. CommonsBeanUtils1 from ysoserial). Solution for this vulnerability: * For Apache Tapestry 5.4.0 to 5.6.1, upgrade to 5.6.2 or later. * For Apache Tapestry 5.7.0, upgrade to 5.7.1 or later.
Metrics
NVD enrichment efforts reference publicly available information to associate
vector strings. CVSS information contributed by other sources is also
displayed.
CVSS 4.0 Severity and Vector Strings:
NVD assessment
not yet provided.
CVSS 3.x Severity and Vector Strings:
Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0 Severity and Vector Strings:
Vector:
(AV:N/AC:L/Au:N/C:C/I:C/A:C)
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Weakness Enumeration
| CWE-ID |
CWE Name |
Source |
|
CWE-502
|
Deserialization of Untrusted Data |
👁 cwe source acceptance level
NIST
Apache Software Foundation
|
|
CWE-200
|
Exposure of Sensitive Information to an Unauthorized Actor |
Apache Software Foundation
|
Change History
7 change records found show changes
CVE Modified by Apache Software Foundation
6/16/2026 11:45:30 PM
| Action |
Type |
Old Value |
New Value |
| Added |
Affected |
[{"vendor":"Apache Software Foundation","product":"Apache Tapestry","versions":[{"version":"Apache Tapestry 5.5.0","status":"affected"},{"version":"Apache Tapestry 5.7.0","status":"affected"},{"version":"Apache Tapestry 5.4.5","lessThan":"Apache Tapestry 5.4.0*","versionType":"custom","status":"affected"},{"version":"Apache Tapestry 5.6.2","lessThan":"Apache Tapestry 5.6.0*","versionType":"custom","status":"affected"}]}]
|
CVE Modified by CVE
11/21/2024 12:58:38 AM
| Action |
Type |
Old Value |
New Value |
| Added |
Reference |
http://www.openwall.com/lists/oss-security/2021/04/15/1
|
| Added |
Reference |
https://lists.apache.org/thread.html/r237ff7f286bda31682c254550c1ebf92b0ec61329b32fbeb2d1c8751%40%3Cusers.tapestry.apache.org%3E
|
| Added |
Reference |
https://security.netapp.com/advisory/ntap-20210528-0002/
|
CVE Modified by Apache Software Foundation
5/14/2024 4:40:34 AM
| Action |
Type |
Old Value |
New Value |
Modified Analysis by NIST
6/02/2021 11:15:24 AM
| Action |
Type |
Old Value |
New Value |
| Changed |
Reference Type |
https://security.netapp.com/advisory/ntap-20210528-0002/ No Types Assigned
|
https://security.netapp.com/advisory/ntap-20210528-0002/ Third Party Advisory
|
CVE Modified by Apache Software Foundation
5/28/2021 6:15:08 AM
| Action |
Type |
Old Value |
New Value |
| Added |
Reference |
https://security.netapp.com/advisory/ntap-20210528-0002/ [No Types Assigned]
|
Initial Analysis by NIST
4/22/2021 9:07:46 AM
| Action |
Type |
Old Value |
New Value |
| Added |
CVSS V3.1 |
NIST AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
|
| Added |
CVSS V2 |
NIST (AV:N/AC:L/Au:N/C:C/I:C/A:C)
|
| Added |
CWE |
NIST CWE-502
|
| Added |
CPE Configuration |
OR
*cpe:2.3:a:apache:tapestry:*:*:*:*:*:*:*:* versions from (including) 5.4.0 up to (excluding) 5.6.2
*cpe:2.3:a:apache:tapestry:*:*:*:*:*:*:*:* versions from (including) 5.7.0 up to (excluding) 5.7.1
|
| Changed |
Reference Type |
http://www.openwall.com/lists/oss-security/2021/04/15/1 No Types Assigned
|
http://www.openwall.com/lists/oss-security/2021/04/15/1 Exploit, Mailing List, Third Party Advisory
|
| Changed |
Reference Type |
https://lists.apache.org/thread.html/r237ff7f286bda31682c254550c1ebf92b0ec61329b32fbeb2d1c8751%40%3Cusers.tapestry.apache.org%3E No Types Assigned
|
https://lists.apache.org/thread.html/r237ff7f286bda31682c254550c1ebf92b0ec61329b32fbeb2d1c8751%40%3Cusers.tapestry.apache.org%3E Mailing List, Vendor Advisory
|
CVE Modified by Apache Software Foundation
4/15/2021 8:15:13 AM
| Action |
Type |
Old Value |
New Value |
| Added |
Reference |
http://www.openwall.com/lists/oss-security/2021/04/15/1 [No Types Assigned]
|
Quick Info
CVE Dictionary Entry: CVE-2021-27850 NVD
Published Date: 04/15/2021 NVD
Last Modified: 06/16/2026
Source: Apache Software Foundation
|
