Vulnerability-Lookup

RHSA-2026:57638

Vulnerability from csaf_redhat - Published: 2026-08-20 17:59 - Updated: 2026-08-25 02:06

Summary

Red Hat Security Advisory: python-urwid security update

Severity

Important

Notes

Topic: An update for python-urwid is now available for Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support and Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Details: Python is an interpreted, interactive, object-oriented programming language, which includes modules, classes, exceptions, very high level dynamic data types and dynamic typing. Python supports interfaces to many system calls and libraries, as well as to various windowing systems. Security Fix(es): * urwid: Urwid: Predictable session IDs lead to remote code execution and information disclosure (CVE-2026-9323) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Terms of Use: This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Red Hat Inc. and provide a link to the original.

CVE-2026-9323

A flaw was found in the urwid web display backend. This vulnerability arises from the use of a cryptographically insecure pseudo-random number generator (PRNG) for web session identifiers, making them predictable. An attacker could either observe enough session IDs to reconstruct the PRNG state or, if local, enumerate active session tokens from temporary files. Successful exploitation allows an attacker to read a victim's terminal screen, inject keystrokes leading to operating system-level code execution, or cause a denial of service by terminating the session.

8.1 (High)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE-1241 - Use of Predictable Algorithm in Random Number Generator

Affected products

Fixed 8 products

Product	Version	Remediation
Unresolved product id: BaseOS-8.4.0.Z.AUS:python-urwid-0:1.3.1-4.el8_4.1.src	—	Vendor Fix fix Workaround
Unresolved product id: BaseOS-8.4.0.Z.AUS:python-urwid-debugsource-0:1.3.1-4.el8_4.1.x86_64	—	Vendor Fix fix Workaround
Unresolved product id: BaseOS-8.4.0.Z.AUS:python3-urwid-0:1.3.1-4.el8_4.1.x86_64	—	Vendor Fix fix Workaround
Unresolved product id: BaseOS-8.4.0.Z.AUS:python3-urwid-debuginfo-0:1.3.1-4.el8_4.1.x86_64	—	Vendor Fix fix Workaround
Unresolved product id: BaseOS-8.4.0.Z.EUS.EXTENSION:python-urwid-0:1.3.1-4.el8_4.1.src	—	Vendor Fix fix Workaround
Unresolved product id: BaseOS-8.4.0.Z.EUS.EXTENSION:python-urwid-debugsource-0:1.3.1-4.el8_4.1.x86_64	—	Vendor Fix fix Workaround
Unresolved product id: BaseOS-8.4.0.Z.EUS.EXTENSION:python3-urwid-0:1.3.1-4.el8_4.1.x86_64	—	Vendor Fix fix Workaround
Unresolved product id: BaseOS-8.4.0.Z.EUS.EXTENSION:python3-urwid-debuginfo-0:1.3.1-4.el8_4.1.x86_64	—	Vendor Fix fix Workaround

Threats

Impact Important

References

14 references

URL	Category
https://access.redhat.com/errata/RHSA-2026:57638	self
https://access.redhat.com/security/updates/classi…	external
https://bugzilla.redhat.com/show_bug.cgi?id=2502072	external
https://security.access.redhat.com/data/csaf/v2/a…	self
https://access.redhat.com/security/cve/CVE-2026-9323	self
https://bugzilla.redhat.com/show_bug.cgi?id=2502072	external
https://www.cve.org/CVERecord?id=CVE-2026-9323	external
https://nvd.nist.gov/vuln/detail/CVE-2026-9323	external
https://github.com/urwid/urwid	external
https://github.com/urwid/urwid/commit/24acd12f0d0…	external
https://github.com/urwid/urwid/issues/1127	external
https://github.com/urwid/urwid/pull/1128	external
https://github.com/urwid/urwid/security/advisorie…	external
https://www.vulncheck.com/advisories/insecure-prn…	external

JSON

To clipboard

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          "title": "Vulnerability description"
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          "text": "urwid: Urwid: Predictable session IDs lead to remote code execution and information disclosure",
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          "details": "To mitigate this vulnerability, it is recommended to disable the urwid web display backend if its functionality is not essential for your environment. If the urwid web display backend must remain active, restrict network access to the service to trusted clients only by implementing appropriate firewall rules. This will limit the exposure to remote attackers attempting to reconstruct session IDs. Additionally, ensure that local system configurations prevent unauthorized access to temporary files, which could otherwise allow local users to enumerate active session tokens. Any changes to service configurations may require a service restart to take effect.",
          "product_ids": [
            "BaseOS-8.4.0.Z.AUS:python-urwid-0:1.3.1-4.el8_4.1.src",
            "BaseOS-8.4.0.Z.AUS:python-urwid-debugsource-0:1.3.1-4.el8_4.1.x86_64",
            "BaseOS-8.4.0.Z.AUS:python3-urwid-0:1.3.1-4.el8_4.1.x86_64",
            "BaseOS-8.4.0.Z.AUS:python3-urwid-debuginfo-0:1.3.1-4.el8_4.1.x86_64",
            "BaseOS-8.4.0.Z.EUS.EXTENSION:python-urwid-0:1.3.1-4.el8_4.1.src",
            "BaseOS-8.4.0.Z.EUS.EXTENSION:python-urwid-debugsource-0:1.3.1-4.el8_4.1.x86_64",
            "BaseOS-8.4.0.Z.EUS.EXTENSION:python3-urwid-0:1.3.1-4.el8_4.1.x86_64",
            "BaseOS-8.4.0.Z.EUS.EXTENSION:python3-urwid-debuginfo-0:1.3.1-4.el8_4.1.x86_64"
          ]
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "products": [
            "BaseOS-8.4.0.Z.AUS:python-urwid-0:1.3.1-4.el8_4.1.src",
            "BaseOS-8.4.0.Z.AUS:python-urwid-debugsource-0:1.3.1-4.el8_4.1.x86_64",
            "BaseOS-8.4.0.Z.AUS:python3-urwid-0:1.3.1-4.el8_4.1.x86_64",
            "BaseOS-8.4.0.Z.AUS:python3-urwid-debuginfo-0:1.3.1-4.el8_4.1.x86_64",
            "BaseOS-8.4.0.Z.EUS.EXTENSION:python-urwid-0:1.3.1-4.el8_4.1.src",
            "BaseOS-8.4.0.Z.EUS.EXTENSION:python-urwid-debugsource-0:1.3.1-4.el8_4.1.x86_64",
            "BaseOS-8.4.0.Z.EUS.EXTENSION:python3-urwid-0:1.3.1-4.el8_4.1.x86_64",
            "BaseOS-8.4.0.Z.EUS.EXTENSION:python3-urwid-debuginfo-0:1.3.1-4.el8_4.1.x86_64"
          ]
        }
      ],
      "threats": [
        {
          "category": "impact",
          "details": "Important"
        }
      ],
      "title": "urwid: Urwid: Predictable session IDs lead to remote code execution and information disclosure"
    }
  ]
}

CVE-2026-9323 (GCVE-0-2026-9323)

Vulnerability from cvelistv5 – Published: 2026-07-18 13:51 – Updated: 2026-07-20 19:31

Title

Insecure PRNG and Information Exposure in urwid Web Display Backend

Summary

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

Severity

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

8.1 (High)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-20 19:26 UTC

CWE

CWE-338 - Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

Assigner

VulnCheck mitre root

References

6 references

URL	Tags
https://github.com/urwid/urwid/security/advisorie…	vendor-advisory
https://github.com/urwid/urwid	product
https://github.com/urwid/urwid/commit/24acd12f0d0…	patch
https://github.com/urwid/urwid/issues/1127	issue-tracking
https://github.com/urwid/urwid/pull/1128	issue-tracking
https://www.vulncheck.com/advisories/insecure-prn…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version
urwid	urwid	Affected: 0 , ≤ 24acd12 (git)

Date Public

2026-07-18 00:00

Credits

Katriel Moses

Show details on NVD website

JSON

To clipboard

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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

RHSA-2026:57638

CVE-2026-9323 (GCVE-0-2026-9323)

Tags

Sightings

Nomenclature