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Python CVE-2026-9323

| EUVDEUVD-2026-45381 CRITICAL
Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) (CWE-338)
2026-07-18 VulnCheck GHSA-83x9-8wvq-rrcp
RCE Python Urwid Red Hat Suse
9.2
CVSS 4.0 · Vendor: VulnCheck
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Severity by source

Vendor (VulnCheck) PRIMARY
9.2 CRITICAL
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/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
SUSE
8.1 HIGH
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Red Hat
8.1 HIGH
qualitative

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/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
Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

3
Source Code Evidence Fetched
Jul 18, 2026 - 14:31 vuln.today
Analysis Generated
Jul 18, 2026 - 14:31 vuln.today
CVE Published
Jul 18, 2026 - 13:51 cve.org
CRITICAL 9.2

DescriptionCVE.org

The urwid web display backend (urwid/display/web.py) generates web session identifiers (urwid_id) in Screen.start() by concatenating two random.randrange(10**9) calls that use Python's Mersenne Twister PRNG, which is not cryptographically secure. Each call consumes approximately 30 bits of PRNG state, and the Mersenne Twister internal state is approximately 19,937 bits, so an attacker who observes approximately 334 session IDs (for example via the X-Urwid-ID HTTP response header) can fully reconstruct the internal state and predict all past and future session IDs (Path B). The same identifier is also used as the filename of a FIFO created in the world-listable /tmp directory (for example /tmp/urwid375487765176907690.in), so any local user on the host can list /tmp to enumerate active session tokens directly (Path A). With a valid session ID, an attacker can read the victim's terminal screen via the polling endpoint, inject keystrokes into the victim's session (yielding OS-level code execution with the session owner's privileges if the session runs a shell), and inject exit sequences or flood the FIFO to terminate or crash the session. A prior Bandit S311 warning on this usage was suppressed with

noqa: S311 rather than fixed

Articles & Coverage 1

News Critical Session Hijacking & RCE in urwid Python Library - CVE-2026-9323 Jul 19, 2026

AnalysisAI

Session hijacking and keystroke injection in the urwid Python library's web display backend (urwid/display/web.py) let attackers take over active web terminal sessions and reach OS-level code execution with the session owner's privileges. The urwid_id session token is generated with Python's non-cryptographic Mersenne Twister PRNG, so a remote attacker who observes roughly 334 session IDs (e.g. …

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Vendor StatusVendor

SUSE

Severity: Important
Product Status
openSUSE Tumbleweed Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS Affected
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS Affected
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS Affected
SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS Affected

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CVE-2026-9323 vulnerability details – vuln.today
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