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CVE-2026-31842

Tinyproxy HTTP request parsing desynchronization via case-sensitive Transfer-Encoding handling

8.7 High

Tinyproxy through 1.11.3 is vulnerable to HTTP request parsing desynchronization due to a case-sensitive comparison of the Transfer-Encoding header in src/reqs.c. The is_chunked_transfer function uses strcmp to compare the header value against "chunked", even though RFC 7230 specifies that transfer-coding names are case-insensitive.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.58%Up 0.5 points since Apr 7, 2026
90%50%10%1%

What each source reports

CVE List Score used 8.7

Tinyproxy HTTP request parsing desynchronization via case-sensitive Transfer-Encoding handling

Tinyproxy through 1.11.3 is vulnerable to HTTP request parsing desynchronization due to a case-sensitive comparison of the Transfer-Encoding header in src/reqs.c. The is_chunked_transfer function uses strcmp to compare the header value against "chunked", even though RFC 7230 specifies that transfer-coding names are case-insensitive.

Record
CVE-2026-31842
CVSS 4.0
8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0
7.8 AV:N/AC:L/Au:N/C:N/I:N/A:C
Weakness
CWE-444
Updated
2026-11-02
EUVDEUVD-2026-19603 8.7

Tinyproxy through 1.11.3 is vulnerable to HTTP request parsing desynchronization due to a case-sensitive comparison of the Transfer-Encoding header in src/reqs.c. The is_chunked_transfer function uses strcmp to compare the header value against "chunked", even though RFC 7230 specifies that transfer-coding names are case-insensitive.

Record
EUVD-2026-19603
CVSS 4.0
8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-mh87-c4c3-cgwf 8.7

Tinyproxy through 1.11.3 is vulnerable to HTTP request parsing desynchronization due to a case...

Tinyproxy through 1.11.3 is vulnerable to HTTP request parsing desynchronization due to a case-sensitive comparison of the Transfer-Encoding header in src/reqs.c. The is_chunked_transfer() function uses strcmp() to compare the header value against "chunked", even though RFC 7230 specifies that transfer-coding names are case-insensitive. By sending a request with Transfer-Encoding: Chunked, an unauthenticated remote attacker can cause Tinyproxy to misinterpret the request as having no body. In this state, Tinyproxy sets content_length.client to -1, skips pull_client_data_chunked(), forwards request headers upstream, and transitions into relay_connection() raw TCP forwarding while unread body data remains buffered. This leads to inconsistent request state between Tinyproxy and backend servers. RFC-compliant backends (e.g., Node.js, Nginx) will continue waiting for chunked body data, causing connections to hang indefinitely. This behavior enables application-level denial of service through backend worker exhaustion. Additionally, in deployments where Tinyproxy is used for request-body inspection, filtering, or security enforcement, the unread body may be forwarded without proper inspection, resulting in potential security control bypass.

Record
GHSA-mh87-c4c3-cgwf
CVSS 4.0
8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-444
Updated
2026-11-02
NVD 8.7

Tinyproxy through 1.11.3 is vulnerable to HTTP request parsing desynchronization due to a case-sensitive comparison of the Transfer-Encoding header in src/reqs.c. The is_chunked_transfer function uses strcmp to compare the header value against "chunked", even though RFC 7230 specifies that transfer-coding names are case-insensitive.

Record
CVE-2026-31842
CVSS 4.0
8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0
7.8 HighAV:N/AC:L/Au:N/C:N/I:N/A:C
Weakness
CWE-444
Updated
2026-11-02
OSV 8.7

Tinyproxy HTTP request parsing desynchronization via case-sensitive Transfer-Encoding handling

Tinyproxy through 1.11.3 is vulnerable to HTTP request parsing desynchronization due to a case-sensitive comparison of the Transfer-Encoding header in src/reqs.c. The is_chunked_transfer function uses strcmp to compare the header value against "chunked", even though RFC 7230 specifies that transfer-coding names are case-insensitive.

Record
CVE-2026-31842
CVSS 4.0
8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-444
Updated
2026-11-02
OSVDEBIAN-CVE-2026-31842 8.7

Tinyproxy through 1.11.3 is vulnerable to HTTP request parsing desynchronization due to a case-sensitive comparison of the Transfer-Encoding header in src/reqs.c. The is_chunked_transfer function uses strcmp to compare the header value against "chunked", even though RFC 7230 specifies that transfer-coding names are case-insensitive.

Record
DEBIAN-CVE-2026-31842
CVSS 4.0
8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Updated
2026-11-02
OSVUBUNTU-CVE-2026-31842 8.7

Tinyproxy through 1.11.3 is vulnerable to HTTP request parsing desynchronization due to a case-sensitive comparison of the Transfer-Encoding header in src/reqs.c. The is_chunked_transfer function uses strcmp to compare the header value against "chunked", even though RFC 7230 specifies that transfer-coding names are case-insensitive.

Record
UBUNTU-CVE-2026-31842
CVSS 4.0
8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
tinyproxy
Debian:12
All versions, plus listed versions
1.11.1-2.11.11.1-2.1+deb12u11.11.1-31.11.1-41.11.2-11.11.2-1~bpo12+11.11.3-11.11.3-1~bpo13+1
None known
tinyproxy
Debian:13
All versions, plus listed versions
1.11.2-11.11.3-11.11.3-1~bpo13+1
None known
tinyproxy
Debian:14
All versions, plus listed versions
1.11.2-11.11.3-11.11.3-1~bpo13+1
None known
tinyproxy
Ubuntu:Pro:14.04:LTS
All versions, plus listed versions
1.8.3-3ubuntu11.8.3-3ubuntu14.04.1~esm11.8.3-3ubuntu14.04.1~esm21.8.3-3ubuntu14.04.1~esm3
None known
tinyproxy
Ubuntu:Pro:16.04:LTS
All versions, plus listed versions
1.8.3-3ubuntu11.8.3-3ubuntu16.04.1~esm11.8.3-3ubuntu16.04.1~esm21.8.3-3ubuntu16.04.1~esm3
None known
tinyproxy
Ubuntu:Pro:18.04:LTS
All versions, plus listed versions
1.8.4-21.8.4-31.8.4-51.8.4-5ubuntu0.1~esm11.8.4-5ubuntu0.1~esm21.8.4-5ubuntu0.1~esm3
None known
tinyproxy
Ubuntu:20.04:LTS
All versions, plus listed versions
1.10.0-21.10.0-41.10.0-4ubuntu0.11.10.0-4ubuntu0.2
None known
tinyproxy
Ubuntu:Pro:22.04:LTS
All versions, plus listed versions
1.10.0-51.11.0-11.11.0-1ubuntu0.1~esm11.11.0-1ubuntu0.1~esm2
None known
tinyproxy
Ubuntu:24.04:LTS
All versions, plus listed versions
1.11.1-2.11.11.1-31.11.1-3ubuntu0.1
None known
tinyproxy
Ubuntu:25.10
All versions, plus listed versions
1.11.2-1
None known
tinyproxy
Ubuntu:26.10
All versions, plus listed versions
1.11.3-1
None known
tinyproxy
Ubuntu:26.04:LTS
All versions, plus listed versions
1.11.2-11.11.2-1build11.11.3-1
None known

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-31842 is a high vulnerability (CVSS 8.7) in Tinyproxy Project Tinyproxy, published April 7, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.58%, the 48th percentile. No source names a fixed version.

References

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