Medium
undertow — security advisory
A flaw was found in Undertow. A regression in the fix for CVE-2020-10687 was found. HTTP request smuggling related to CVE-2017-2666 is possible against HTTP/1.x and HTTP/2 due to permitting invalid characters in an HTTP request. This flaw allows an attacker to poison a web-cache, perform an XSS attack, or obtain sensitive information from request other than their own. The highest threat from this vulnerability is to data confidentiality and integrity.
- Products
- undertow
- Affected versions
- 1.3.11-1, 1.3.16-1, 1.3.16-1ubuntu0.1~esm1, 1.3.4-1, 1.3.5-1, 1.3.7-1, 1.4.20-1, 1.4.21-1, 1.4.22-1, 1.4.23-1, 1.4.23-2build1, 1.4.23-3, 1.4.23-3ubuntu0.1~esm1, 2.0.23-1, 2.0.27-1, 2.0.28-1, 2.0.29-1, 2.0.29-1ubuntu0.1~esm1, 2.2.12-1, 2.2.13-1, 2.2.14-1, 2.2.16-1, 2.2.16-1ubuntu0.1~esm1, 2.2.8-1, 2.3.18-1, 2.3.18-2, 2.3.20-1, 2.3.20-1ubuntu1, 2.3.8-2, 2.3.8-2ubuntu0.1~esm1
- Fixed versions
- Not specified
- CVEs
- CVE-2021-20220
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 00:58 UTC · Revision 1
Source evidence
A flaw was found in Undertow. A regression in the fix for CVE-2020-10687 was found. HTTP request smuggling related to CVE-2017-2666 is possible against HTTP/1.x and HTTP/2 due to permitting invalid characters in an HTTP request. This flaw allows an attacker to poison a web-cache, perform an XSS attack, or obtain sensitive information from request other than their own. The highest threat from this vulnerability is to data confidentiality and integrity.
osv:UBUNTU-CVE-2021-20220
undertow
Fixed versions: Not specified
undertow
Fixed versions: Not specified
undertow
Fixed versions: Not specified
undertow
Fixed versions: Not specified
undertow
Fixed versions: Not specified
undertow
Fixed versions: Not specified
undertow
Fixed versions: Not specified
undertow
Fixed versions: Not specified
Complete source record
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"modified": "2026-10-17T12:56:19.360264577Z",
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