Bug 2535043 - CVE-2026-56123 socat: Socat: Heap-based buffer overflow allows arbitrary code execution via malicious SOCKS5 proxy server [fedora-all]
Summary: CVE-2026-56123 socat: Socat: Heap-based buffer overflow allows arbitrary code...
Keywords:
Status: NEW
Alias: None
Product: Fedora
Classification: Fedora
Component: socat
Version: rawhide
Hardware: Unspecified
OS: Unspecified
high
high
Target Milestone: ---
Assignee: Paul Wouters
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard: {"flaws": ["0090ee98-5aa8-4795-b6ca-3...
Depends On:
Blocks: CVE-2026-56123
TreeView+ depends on / blocked
 
Reported: 2026-09-16 08:11 UTC by Tomas Hoger
Modified: 2026-09-16 08:11 UTC (History)
3 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Type: ---
Embargoed:
fedora-admin-xmlrpc: mirror+


Attachments (Terms of Use)

Description Tomas Hoger 2026-09-16 08:11:39 UTC
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

socat versions 1.8.0.0 through 1.8.1.1 contain a heap-based buffer overflow vulnerability that allows a malicious SOCKS5 proxy server to overwrite adjacent heap memory by exploiting a sign-extension flaw in the DOMAINNAME reply parser. During connection setup, the domain name length byte is read through a signed char field causing a negative bytes_to_read value that is implicitly converted to size_t, resulting in an unbounded heap write into the 262-byte reply buffer with attacker-controlled size and content.


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