Vulnerability in OWASP AntiSamy (CVE-2021-35043)

Summary

Vulnerability in OWASP AntiSamy (CVE-2021-35043). Risk of unauthorized operations or information disclosure.

Original description

The description as published by the source.

OWASP AntiSamy before 1.6.4 allows XSS via HTML attributes when using the HTML output serializer (XHTML is not affected). This was demonstrated by a javascript: URL with &#00058 as the replacement for the : character.

Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2021-35043 has been found in OWASP AntiSamy.
Risk of unauthorized operations or information disclosure.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "OWASP AntiSamy CVE-2021-35043" on the vendor's site.

CVE-2021-35043 (OWASP AntiSamy)
Attack vector: remote (network-reachable) / unauthenticated
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (unclassified) exists in OWASP AntiSamy.

📍 Affected scope

Check the vendor advisory for the affected versions of OWASP AntiSamy.

🔥 Severity

Severity: ?. Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

1
Identify exposure identify
```
Audit SBOM/dependencies for affected components.
```
資産台帳・SBOM・依存マニフェストで OWASP AntiSamy を使っているサービスとバージョンを洗い出す。
2
Post-deployment verification verify
```
Confirm patched version is live in production
```
パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Fix status by distribution

Fixed packages published by each distribution for this CVE

Ubuntu UBUNTU-CVE-2021-35043 libowasp-antisamy-java

References

patch github.com
patch github.com
patch oracle.com
patch oracle.com
patch oracle.com
patch oracle.com