CVE-2026-3945

NameCVE-2026-3945
DescriptionAn 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.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
tinyproxy (PTS)bullseye1.10.0-5vulnerable
bullseye (security)1.10.0-5+deb11u1vulnerable
bookworm, bookworm (security)1.11.1-2.1+deb12u1vulnerable
trixie1.11.2-1vulnerable
forky, sid1.11.3-1vulnerable

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
tinyproxysource(unstable)(unfixed)

Notes

https://github.com/tinyproxy/tinyproxy/issues/602
https://github.com/tinyproxy/tinyproxy/pull/603

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