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CVE-2026-3945

tinyproxy Integer Overflow in HTTP Chunked Transfer-Encoding Parser Leading to Denial of Service

8.7 HighFix available

An integer overflow vulnerability in the HTTP chunked transfer encoding parser in tinyproxy up to and including version 1.11.3 allows an unauthenticated remote attacker to cause a denial of service (DoS). The issue occurs because chunk size values are parsed using strtol without properly validating overflow conditions (e.g., errno == ERANGE).

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

0.60%Up 0.6 points since Mar 30, 2026
90%50%10%1%

What each source reports

CVE List Score used 8.7

tinyproxy Integer Overflow in HTTP Chunked Transfer-Encoding Parser Leading to Denial of Service

An integer overflow vulnerability in the HTTP chunked transfer encoding parser in tinyproxy up to and including version 1.11.3 allows an unauthenticated remote attacker to cause a denial of service (DoS). The issue occurs because chunk size values are parsed using strtol without properly validating overflow conditions (e.g., errno == ERANGE).

Record
CVE-2026-3945
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-190
Updated
2026-11-02
EUVDEUVD-2026-17066 8.7

An integer overflow vulnerability in the HTTP chunked transfer encoding parser in tinyproxy up to and including version 1.11.3 allows an unauthenticated remote attacker to cause a denial of service (DoS). The issue occurs because chunk size values are parsed using strtol without properly validating overflow conditions (e.g., errno == ERANGE).

Record
EUVD-2026-17066
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-6vhj-8f7g-v7f7 8.7

An integer overflow vulnerability in the HTTP chunked transfer encoding parser in tinyproxy up to...

An integer overflow vulnerability in the HTTP chunked transfer encoding parser in tinyproxy up to and including version 1.11.3 allows an unauthenticated remote attacker to cause a denial of service (DoS). The issue occurs because chunk size values are parsed using strtol() without properly validating overflow conditions (e.g., errno == ERANGE). A crafted chunk size such as 0x7fffffffffffffff (LONG_MAX) bypasses the existing validation check (chunklen < 0), leading to a signed integer overflow during arithmetic operations (chunklen + 2). This results in incorrect size calculations, causing the proxy to attempt reading an extremely large amount of request-body data and holding worker connections open indefinitely. An attacker can exploit this behavior to exhaust all available worker slots, preventing new connections from being accepted and causing complete service unavailability. Upstream addressed this issue in commit bb7edc4; however, the latest stable release (1.11.3) remains affected at the time of publication.

Record
GHSA-6vhj-8f7g-v7f7
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-190
Updated
2026-11-02
NVD 8.7

An integer overflow vulnerability in the HTTP chunked transfer encoding parser in tinyproxy up to and including version 1.11.3 allows an unauthenticated remote attacker to cause a denial of service (DoS). The issue occurs because chunk size values are parsed using strtol without properly validating overflow conditions (e.g., errno == ERANGE).

Record
CVE-2026-3945
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-190
Updated
2026-11-02
OSV 8.7

tinyproxy Integer Overflow in HTTP Chunked Transfer-Encoding Parser Leading to Denial of Service

An integer overflow vulnerability in the HTTP chunked transfer encoding parser in tinyproxy up to and including version 1.11.3 allows an unauthenticated remote attacker to cause a denial of service (DoS). The issue occurs because chunk size values are parsed using strtol without properly validating overflow conditions (e.g., errno == ERANGE).

Record
CVE-2026-3945
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-190
Updated
2026-11-02
OSVDEBIAN-CVE-2026-3945 8.7

An integer overflow vulnerability in the HTTP chunked transfer encoding parser in tinyproxy up to and including version 1.11.3 allows an unauthenticated remote attacker to cause a denial of service (DoS). The issue occurs because chunk size values are parsed using strtol without properly validating overflow conditions (e.g., errno == ERANGE).

Record
DEBIAN-CVE-2026-3945
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-2026-3945 8.7

An integer overflow vulnerability in the HTTP chunked transfer encoding parser in tinyproxy up to and including version 1.11.3 allows an unauthenticated remote attacker to cause a denial of service (DoS). The issue occurs because chunk size values are parsed using strtol without properly validating overflow conditions (e.g., errno == ERANGE).

Record
UBUNTU-CVE-2026-3945
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
OSVopenSUSE-SU-2026:10471-1 No score

tinyproxy-1.11.3-2.1 on GA media

These are all security issues fixed in the tinyproxy-1.11.3-2.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2026:10471-1
Updated
2026-11-02
OSVopenSUSE-SU-2026:20456-1 No score

Security update for tinyproxy

This update for tinyproxy fixes the following issues:

Changes in tinyproxy:

  • CVE-2026-3945: Fixed denial of service by unauthenticated remote attacker (boo#1261024)

  • Update to release 1.11.3

    • conf: add BasicAuthRealm feature
    • basic auth: fix error status 401 vs 407
    • tinyproxy.conf.5: explain what a site_spec looks like
    • tinyproxy.conf.5: add an IPv6 example to allow/deny section
    • reqs: fix integer overflow in port number processing
Record
openSUSE-SU-2026:20456-1
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
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Affected packages
PackageAffectedFixed
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
tinyproxy
openSUSE:Tumbleweed
before 1.11.3-2.1
1.11.3-2.1
tinyproxy
openSUSE:Leap 16.0
before 1.11.3-bp160.1.1
1.11.3-bp160.1.1

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-2026-3945 is a high vulnerability (CVSS 8.7) in Tinyproxy, published March 30, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.60%, the 49th percentile. Fixed in tinyproxy 1.11.3-2.1.

References

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