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6 vulnerabilities by python-hyper
CVE-2026-71554 (GCVE-0-2026-71554)
Vulnerability from nvd – Published: 2026-08-06 21:46 – Updated: 2026-08-08 02:49
VLAI
EPSS
VEX
Title
h2: Duplicate Host header could facilitate request smuggling
Summary
h2 is a pure-Python implementation of a HTTP/2 protocol stack. Versions up to and including 4.4.0 accept request header blocks containing more than one Host header, and forward every Host header to the consuming application. Where the consumer downgrades HTTP/2 to HTTP/1.1, the resulting request carries two Host header lines, providing a request smuggling primitive. This issue is fixed in version 4.4.1.
Severity
5.3 (Medium)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://github.com/python-hyper/h2/security/advis… | x_refsource_CONFIRM |
| https://github.com/python-hyper/h2/commit/292a408… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| python-hyper | h2 |
Affected:
< 4.4.1
|
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CVE-2025-57804 (GCVE-0-2025-57804)
Vulnerability from nvd – Published: 2025-08-25 21:04 – Updated: 2025-11-03 18:13
VLAI
EPSS
VEX
Title
h2 allows HTTP Request Smuggling due to illegal characters in headers
Summary
h2 is a pure-Python implementation of a HTTP/2 protocol stack. Prior to version 4.3.0, an HTTP/2 request splitting vulnerability allows attackers to perform request smuggling attacks by injecting CRLF characters into headers. This occurs when servers downgrade HTTP/2 requests to HTTP/1.1 without properly validating header names/values, enabling attackers to manipulate request boundaries and bypass security controls. This issue has been patched in version 4.3.0.
Severity
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-93 - Improper Neutralization of CRLF Sequences ('CRLF Injection')
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/python-hyper/h2/security/advis… | x_refsource_CONFIRM |
| https://github.com/python-hyper/h2/commit/035e989… | x_refsource_MISC |
| https://lists.debian.org/debian-lts-announce/2025… |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| python-hyper | h2 |
Affected:
< 4.3.0
|
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CVE-2025-43859 (GCVE-0-2025-43859)
Vulnerability from nvd – Published: 2025-04-24 18:15 – Updated: 2025-04-24 19:02
VLAI
EPSS
VEX
Title
h11 accepts some malformed Chunked-Encoding bodies
Summary
h11 is a Python implementation of HTTP/1.1. Prior to version 0.16.0, a leniency in h11's parsing of line terminators in chunked-coding message bodies can lead to request smuggling vulnerabilities under certain conditions. This issue has been patched in version 0.16.0. Since exploitation requires the combination of buggy h11 with a buggy (reverse) proxy, fixing either component is sufficient to mitigate this issue.
Severity
9.1 (Critical)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: total
CISA Coordinator (v2.0.3)
CWE
- CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://github.com/python-hyper/h11/security/advi… | x_refsource_CONFIRM |
| https://github.com/python-hyper/h11/commit/114803… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| python-hyper | h11 |
Affected:
< 0.16.0
|
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CVE-2026-71554 (GCVE-0-2026-71554)
Vulnerability from cvelistv5 – Published: 2026-08-06 21:46 – Updated: 2026-08-08 02:49
VLAI
EPSS
VEX
Title
h2: Duplicate Host header could facilitate request smuggling
Summary
h2 is a pure-Python implementation of a HTTP/2 protocol stack. Versions up to and including 4.4.0 accept request header blocks containing more than one Host header, and forward every Host header to the consuming application. Where the consumer downgrades HTTP/2 to HTTP/1.1, the resulting request carries two Host header lines, providing a request smuggling primitive. This issue is fixed in version 4.4.1.
Severity
5.3 (Medium)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://github.com/python-hyper/h2/security/advis… | x_refsource_CONFIRM |
| https://github.com/python-hyper/h2/commit/292a408… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| python-hyper | h2 |
Affected:
< 4.4.1
|
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CVE-2025-57804 (GCVE-0-2025-57804)
Vulnerability from cvelistv5 – Published: 2025-08-25 21:04 – Updated: 2025-11-03 18:13
VLAI
EPSS
VEX
Title
h2 allows HTTP Request Smuggling due to illegal characters in headers
Summary
h2 is a pure-Python implementation of a HTTP/2 protocol stack. Prior to version 4.3.0, an HTTP/2 request splitting vulnerability allows attackers to perform request smuggling attacks by injecting CRLF characters into headers. This occurs when servers downgrade HTTP/2 requests to HTTP/1.1 without properly validating header names/values, enabling attackers to manipulate request boundaries and bypass security controls. This issue has been patched in version 4.3.0.
Severity
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-93 - Improper Neutralization of CRLF Sequences ('CRLF Injection')
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/python-hyper/h2/security/advis… | x_refsource_CONFIRM |
| https://github.com/python-hyper/h2/commit/035e989… | x_refsource_MISC |
| https://lists.debian.org/debian-lts-announce/2025… |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| python-hyper | h2 |
Affected:
< 4.3.0
|
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CVE-2025-43859 (GCVE-0-2025-43859)
Vulnerability from cvelistv5 – Published: 2025-04-24 18:15 – Updated: 2025-04-24 19:02
VLAI
EPSS
VEX
Title
h11 accepts some malformed Chunked-Encoding bodies
Summary
h11 is a Python implementation of HTTP/1.1. Prior to version 0.16.0, a leniency in h11's parsing of line terminators in chunked-coding message bodies can lead to request smuggling vulnerabilities under certain conditions. This issue has been patched in version 0.16.0. Since exploitation requires the combination of buggy h11 with a buggy (reverse) proxy, fixing either component is sufficient to mitigate this issue.
Severity
9.1 (Critical)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: total
CISA Coordinator (v2.0.3)
CWE
- CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://github.com/python-hyper/h11/security/advi… | x_refsource_CONFIRM |
| https://github.com/python-hyper/h11/commit/114803… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| python-hyper | h11 |
Affected:
< 0.16.0
|
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