Answer in brief
CVE-2026-33555 records a Medium severity (CVSS 4.0) vulnerability in CISA ADP Vulnrichment. The current sources do not mark it as known exploited. The current feed maps HAProxy/HAProxy (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 4.0. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps HAProxy/HAProxy (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| HAProxy/HAProxygeneric | >=2.6 <3.3.6 | 3.3.6 |
Published upstream
Apr 13, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jun 29, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jun 29, 2026
An issue was discovered in HAProxy before 3.3.6. The HTTP/3 parser does not check that the received body length matches a previously announced content-length when the stream is closed via a frame with an empty payload. This can cause desynchronization issues with the backend server and could be used for request smuggling. The earliest affected version is 2.6.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2026-33555 records a Medium severity (CVSS 4.0) vulnerability in CISA ADP Vulnrichment. The current sources do not mark it as known exploited. The current feed maps HAProxy/HAProxy (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 4.0. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps HAProxy/HAProxy (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| HAProxy/HAProxygeneric | >=2.6 <3.3.6 | 3.3.6 |
Published upstream
Apr 13, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jun 29, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jun 29, 2026
An issue was discovered in HAProxy before 3.3.6. The HTTP/3 parser does not check that the received body length matches a previously announced content-length when the stream is closed via a frame with an empty payload. This can cause desynchronization issues with the backend server and could be used for request smuggling. The earliest affected version is 2.6.
Quoted source text, attributed separately from HOL analysis.