CVE-2026-9323Public exploitNetwork attack vector

Session hijacking via predictable web identifiers

Published Jul 18, 2026 · Updated Jul 18, 2026

Session identifier weakness in Urwid 4.0.1.dev4+gb94a01454 allows remote attackers to hijack web display sessions. Screen.start() forms urwid_id tokens with predictable Mersenne Twister output and exposes the same tokens in FIFO names under world-listable /tmp. Remote exploitation requires observing about 334 issued identifiers; local users can instead enumerate active tokens, then read terminal output, inject keystrokes, or interrupt the session.

CVSS severity9.2
Critical
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Session identifier weakness in Urwid 4.0.1.dev4+gb94a01454 allows remote attackers to hijack web display sessions. Screen.start() forms urwid_id tokens with predictable Mersenne Twister output and exposes the same tokens in FIFO names under world-listable /tmp. Remote exploitation requires observing about 334 issued identifiers; local users can instead enumerate active tokens, then read terminal output, inject keystrokes, or interrupt the session.

The record

CVE
CVE-2026-9323
Published
Jul 18, 2026
Updated
Jul 18, 2026
Vendor
Urwid
Product
Urwid
Classifications
CWE-338, CWE-330, T1539
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=24acd12

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Urwid · Urwidversion=0 <=24acd12

Published CVSS scores

7.4GitHubCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
9.2VulnCheckCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
8.1VulnCheckCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-338Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)
CWE-330Use of Insufficiently Random Values
T1539Steal Web Session Cookie

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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