⚠ Known Exploited Vulnerability (KEV) Tracker

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.

Lifecycle Timeline

• 2021-04-15
  CVE published

  Entered the public CVE record.

  CVE.org →
• 2021-04-15
  Public exploit code

  Metasploit — Apache Tapestry HMAC secret key leak

  Metasploit →
• 2024-10-10
  First national advisory 3.5 years later

  NSA — Update on SVR Cyber Operations and Vulnerability Exploitation

  CyberzSOC advisory index →
• not recorded
  EPSS flags exploitation risk

  Already at 65.0% when EPSS history begins (2021-12-11), so the moment it was first flagged predates the record.
• not recorded
  Added to CISA KEV

  Not in the CISA KEV catalog.
• not recorded
  Federal remediation due

  No remediation deadline set.
• not recorded
  Vendor fix published

  No dated vendor fix. Only Microsoft publishes a machine-readable release date; other vendors state a fixed version without one.

Each milestone comes from a different source, so gaps between them are gaps in what those sources publish, not evidence that nothing happened. EPSS history for this CVE holds 262 points from 2021-12-11, tracked daily from 2026-09-09; earlier points are weekly, which dates a spike to within a week. Peak probability 97.4% on 2023-10-28.

Published Applicability

Check whether a specific version is affected →

What each source publishes about which product versions carry this vulnerability, kept as written rather than merged. Absence here means no source has published applicability data, not that nothing is affected.

Research & News Coverage

No mentions found in monitored research blogs or news feeds.

Detection & Exploitation

Coverage across public collections only: Nuclei and OpenVAS NVT (scan); Snort and Suricata ET Open (network); Sigma and YARA (host/SIEM); Metasploit, Exploit-DB and public GitHub repositories (exploit). Absence here means nothing public was found, not that detection is impossible.
GitHub PoC repositories are collected automatically by PoC-in-GitHub (CC0) and are not vetted: some are fakes and some are malware. Treat them as evidence that code was published, not as code to run.
OpenVAS coverage derives from the Greenbone Community Feed, made available under the Open Database License (ODbL) v1.0; its individual Vulnerability Tests are licensed GNU GPL v2.

CISA Assessment (Vulnrichment / SSVC)

No CISA Vulnrichment record for this CVE.

Listed By

Referenced in Advisories

Weaponization Timeline — Offensive & Testing Tools

No exploit-tool sightings recorded for this CVE.

Evidence tiers are explained on the About page — a merged Metasploit module is far stronger evidence than a distro package mention.

External References

CVE.org record → NVD entry → FortiGuard Labs → Rapid7 AttackerKB →