vulnerability / NVI-00013961 / Revision 2
Http4s Ember Transfer-Encoding value parsing (TE.CL / TE.0 request smuggling)
GitHub lists this reviewed advisory for org.http4s:http4s-ember-core_3, org.http4s:http4s-ember-core_2.13, org.http4s:http4s-ember-core_2.12, org.http4s:http4s-ember-core_2.13, org.http4s:http4s-ember-core_3. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
8.7 high
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
0.480%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.41391. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
org.http4s:http4s-ember-core_3
source listed<= 0.23.34
## Summary Ember's HTTP/1.1 header parser matches the `Transfer-Encoding` header value with a case-sensitive substring test (`hValue.contains("chunked")`). RFC 9112 §7 requires transfer-coding names to be compared case-insensitively. A request carrying `Transfer-Encoding: Chunked` (capital C) is therefore not recognised as chunked, and Ember falls back to framing by `Content-Length` (or zero if absent) while a compliant intermediary frames the same bytes by chunked encoding. The two parsers then disagree on where the request body ends, enabling HTTP request smuggling (TE.CL / TE.0). The same line of code admits two further variants: - The substring test misfires on `Transfer-Encoding: notchunked` (an inverse desync — Ember treats it as chunked while a compliant intermediary rejects the unknown coding). - Header field bytes are decoded with the platform-default charset. Under UTF-8 the wire bytes `E2 84 AA` decode to U+212A KELVIN SIGN, which `String.equalsIgnoreCase` Unicode-case-folds to `k`, so `Transfer-Encoding: chuned` matches `chunked` once the comparison is made case-insensitive without also pinning the decode to ISO-8859-1. ## Impact ### Server Req
org.http4s:http4s-ember-core_2.13
source listed<= 0.23.34
## Summary Ember's HTTP/1.1 header parser matches the `Transfer-Encoding` header value with a case-sensitive substring test (`hValue.contains("chunked")`). RFC 9112 §7 requires transfer-coding names to be compared case-insensitively. A request carrying `Transfer-Encoding: Chunked` (capital C) is therefore not recognised as chunked, and Ember falls back to framing by `Content-Length` (or zero if absent) while a compliant intermediary frames the same bytes by chunked encoding. The two parsers then disagree on where the request body ends, enabling HTTP request smuggling (TE.CL / TE.0). The same line of code admits two further variants: - The substring test misfires on `Transfer-Encoding: notchunked` (an inverse desync — Ember treats it as chunked while a compliant intermediary rejects the unknown coding). - Header field bytes are decoded with the platform-default charset. Under UTF-8 the wire bytes `E2 84 AA` decode to U+212A KELVIN SIGN, which `String.equalsIgnoreCase` Unicode-case-folds to `k`, so `Transfer-Encoding: chuned` matches `chunked` once the comparison is made case-insensitive without also pinning the decode to ISO-8859-1. ## Impact ### Server Req
org.http4s:http4s-ember-core_2.12
source listed<= 0.23.34
## Summary Ember's HTTP/1.1 header parser matches the `Transfer-Encoding` header value with a case-sensitive substring test (`hValue.contains("chunked")`). RFC 9112 §7 requires transfer-coding names to be compared case-insensitively. A request carrying `Transfer-Encoding: Chunked` (capital C) is therefore not recognised as chunked, and Ember falls back to framing by `Content-Length` (or zero if absent) while a compliant intermediary frames the same bytes by chunked encoding. The two parsers then disagree on where the request body ends, enabling HTTP request smuggling (TE.CL / TE.0). The same line of code admits two further variants: - The substring test misfires on `Transfer-Encoding: notchunked` (an inverse desync — Ember treats it as chunked while a compliant intermediary rejects the unknown coding). - Header field bytes are decoded with the platform-default charset. Under UTF-8 the wire bytes `E2 84 AA` decode to U+212A KELVIN SIGN, which `String.equalsIgnoreCase` Unicode-case-folds to `k`, so `Transfer-Encoding: chuned` matches `chunked` once the comparison is made case-insensitive without also pinning the decode to ISO-8859-1. ## Impact ### Server Req
org.http4s:http4s-ember-core_2.13
source listed>= 1.0.0-M1, <= 1.0.0-M46
## Summary Ember's HTTP/1.1 header parser matches the `Transfer-Encoding` header value with a case-sensitive substring test (`hValue.contains("chunked")`). RFC 9112 §7 requires transfer-coding names to be compared case-insensitively. A request carrying `Transfer-Encoding: Chunked` (capital C) is therefore not recognised as chunked, and Ember falls back to framing by `Content-Length` (or zero if absent) while a compliant intermediary frames the same bytes by chunked encoding. The two parsers then disagree on where the request body ends, enabling HTTP request smuggling (TE.CL / TE.0). The same line of code admits two further variants: - The substring test misfires on `Transfer-Encoding: notchunked` (an inverse desync — Ember treats it as chunked while a compliant intermediary rejects the unknown coding). - Header field bytes are decoded with the platform-default charset. Under UTF-8 the wire bytes `E2 84 AA` decode to U+212A KELVIN SIGN, which `String.equalsIgnoreCase` Unicode-case-folds to `k`, so `Transfer-Encoding: chuned` matches `chunked` once the comparison is made case-insensitive without also pinning the decode to ISO-8859-1. ## Impact ### Server Req
org.http4s:http4s-ember-core_3
source listed>= 1.0.0-M1, <= 1.0.0-M46
## Summary Ember's HTTP/1.1 header parser matches the `Transfer-Encoding` header value with a case-sensitive substring test (`hValue.contains("chunked")`). RFC 9112 §7 requires transfer-coding names to be compared case-insensitively. A request carrying `Transfer-Encoding: Chunked` (capital C) is therefore not recognised as chunked, and Ember falls back to framing by `Content-Length` (or zero if absent) while a compliant intermediary frames the same bytes by chunked encoding. The two parsers then disagree on where the request body ends, enabling HTTP request smuggling (TE.CL / TE.0). The same line of code admits two further variants: - The substring test misfires on `Transfer-Encoding: notchunked` (an inverse desync — Ember treats it as chunked while a compliant intermediary rejects the unknown coding). - Header field bytes are decoded with the platform-default charset. Under UTF-8 the wire bytes `E2 84 AA` decode to U+212A KELVIN SIGN, which `String.equalsIgnoreCase` Unicode-case-folds to `k`, so `Transfer-Encoding: chuned` matches `chunked` once the comparison is made case-insensitive without also pinning the decode to ISO-8859-1. ## Impact ### Server Req
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-9998-894r-fwvr ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- CVE-2026-69205 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 2 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.