CVE-2026-31842
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.
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
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 High
CVSS: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 High
CVSS: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 High
CVSS: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 High
CVSS: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 High
CVSS: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 High
CVSS: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 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 2.0
- 7.8 High
AV: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 High
CVSS: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 High
CVSS: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 High
CVSS: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 High
CVSS: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
| Package | Affected | Fixed |
|---|---|---|
tinyproxyDebian: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 |
tinyproxyDebian:13 |
All versions, plus listed versions 1.11.2-11.11.3-11.11.3-1~bpo13+1 |
None known |
tinyproxyDebian:14 |
All versions, plus listed versions 1.11.2-11.11.3-11.11.3-1~bpo13+1 |
None known |
tinyproxyUbuntu: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 |
tinyproxyUbuntu: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 |
tinyproxyUbuntu: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 |
tinyproxyUbuntu: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 |
tinyproxyUbuntu: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 |
tinyproxyUbuntu:24.04:LTS |
All versions, plus listed versions 1.11.1-2.11.11.1-31.11.1-3ubuntu0.1 |
None known |
tinyproxyUbuntu:25.10 |
All versions, plus listed versions 1.11.2-1 |
None known |
tinyproxyUbuntu:26.10 |
All versions, plus listed versions 1.11.3-1 |
None known |
tinyproxyUbuntu:26.04:LTS |
All versions, plus listed versions 1.11.2-11.11.2-1build11.11.3-1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE 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
github.com/tinyproxy/tinyproxy/issues/604
github.com/tinyproxy/tinyproxy
datatracker.ietf.org/doc/html/rfc7230
nvd.nist.gov/vuln/detail/CVE-2026-31842
github.com/advisories/GHSA-mh87-c4c3-cgwf
github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31842.json
security-tracker.debian.org/tracker/CVE-2026-31842
ubuntu.com/security/CVE-2026-31842
cve.org/CVERecord?id=CVE-2026-31842