Use of Predictable Algorithm in Random Number Generator Affecting python3-urwid-debuginfo package, versions <0:2.5.3-4.el10_2.5


Severity

Recommended
0.0
high
0
10

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.42% (35th percentile)

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  • Snyk IDSNYK-RHEL10-PYTHON3URWIDDEBUGINFO-19233804
  • published24 Aug 2026
  • disclosed18 Jul 2026

Introduced: 18 Jul 2026

CVE-2026-9323  (opens in a new tab)
CWE-1241  (opens in a new tab)

How to fix?

Upgrade RHEL:10 python3-urwid-debuginfo to version 0:2.5.3-4.el10_2.5 or higher.
This issue was patched in RHSA-2026:58561.

NVD Description

Note: Versions mentioned in the description apply only to the upstream python3-urwid-debuginfo package and not the python3-urwid-debuginfo package as distributed by RHEL. See How to fix? for RHEL:10 relevant fixed versions and status.

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

CVSS Base Scores

version 3.1