CVE-2026-2439
Bva Concierge\ \
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HSummary
CVE-2026-2439 is a critical-severity PRNG (CWE-338) vulnerability in Bva Concierge\. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Forge Web Credentials (T1606); ranked at the 33th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SC-12 (Cryptographic Key Establishment and Management) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-2439 affects the Concierge::Sessions Perl module in versions from 0.8.1 before 0.8.5, where the generate_session_id function in Concierge::Sessions::Base produces insecure session identifiers. By default, it relies on the uuidgen command, which generates time-based UUIDs if the system lacks a high-quality random number source, as it omits the --random option; system time is often exposed in HTTP responses. If uuidgen fails silently, it falls back to Perl's built-in rand() function, which generates predictable values unsuitable for security contexts. These flaws align with CWE-338 (use of weak or predictable cryptographic primitives) and CWE-340 (generation of predictable numbers or identifiers), earning a CVSS v3.1 score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
Remote attackers without privileges can exploit this vulnerability by guessing session IDs due to their predictability from observable timestamps or sequential rand() outputs. Possession of a valid session ID grants direct access to affected systems, as UUIDs function as bearer tokens per RFC 9562. Successful exploitation enables high confidentiality, integrity, and availability impacts, such as unauthorized session hijacking.
Patches in Concierge::Sessions version 0.8.5 address the issues, as detailed in the GitHub commit (20bb28e92e8fba307c4ff8264701c215be65e73b) and the MetaCPAN release diff, which improve session ID generation to use secure methods. Perl security guidance recommends high-entropy sources for random data, avoiding rand() (perldoc.perl.org/5.42.0/functions/rand) and following best practices in metacpan.org's random-data-for-security guide.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-7824
Vulnerability Data
Concierge::Sessions versions from 0.8.1 before 0.8.5 for Perl generate insecure session ids. The generate_session_id function in Concierge::Sessions::Base defaults to using the uuidgen command to generate a UUID, with a fallback to using Perl's built-in rand function. Neither of these methods…
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are secure, and attackers are able to guess session_ids that can grant them access to systems. Specifically, * There is no warning when uuidgen fails. The software can be quietly using the fallback rand() function with no warnings if the command fails for any reason. * The uuidgen command will generate a time-based UUID if the system does not have a high-quality random number source, because the call does not explicitly specify the --random option. Note that the system time is shared in HTTP responses. * UUIDs are identifiers whose mere possession grants access, as per RFC 9562. * The output of the built-in rand() function is predictable and unsuitable for security applications.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 9 hardening rules · 4 OS baselines
V7.2.3V11.5.1V11.3.4
Mitigating Controls (NIST 800-53 r5) AI
Requiring specific approved cryptography for protection directly mandates use of strong PRNGs instead of weak ones.
Developer testing and evaluation can discover predictable number generation through targeted analysis or fuzzing of identifier creation routines.
Cryptographic key establishment and management mandates proper entropy and randomness during generation, directly stopping predictable identifiers at the source.
Authenticator management requires secure initial distribution and handling of authenticators, structurally preventing predictable values from being usable.
Engineering principles applied during design and development include selection of cryptographically strong random number generation.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices explicitly require cryptographically strong RNG selection and usage in security contexts.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Mandates use of approved cryptographic controls, directly requiring cryptographically strong RNGs.
Security testing can detect use of weak random number generators.
Secure SDLC processes should catch weak PRNG usage during design and code review.
Application security requirements can specify cryptographically strong random number generation.
Secure engineering principles include selection of appropriate cryptographic primitives.
Secure coding standards prohibit use of weak PRNGs in security contexts.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Oracle Linux 8 (3 rules)
- V-248524 OL 8 must implement NIST FIPS-validated cryptography for the following: To provision digital signatures, to generate cryptographic hashes, and to protect data requiring data-at-rest protections in accordance with applicable federal laws, Executive Orders, directives, policies, regulations, and standards. prevents CWE-340
- V-248563 The OL 8 SSH server must be configured to use strong entropy. prevents CWE-338
- V-248600 OL 8 must have the packages required to use the hardware random number generator entropy gatherer service. prevents CWE-340
RHEL 7 (1 rule)
- V-204497 The Red Hat Enterprise Linux operating system must implement NIST FIPS-validated cryptography for the following: to provision digital signatures, to generate cryptographic hashes, and to protect data requiring data-at-rest protections in accordance with applicable federal laws, Executive Orders, directives, policies, regulations, and standards. prevents CWE-340
RHEL 8 (2 rules)
- V-230253 RHEL 8 must ensure the SSH server uses strong entropy. prevents CWE-338
- V-244527 RHEL 8 must have the packages required to use the hardware random number generator entropy gatherer service. prevents CWE-340
Ubuntu 22.04 (1 rule)
- V-260650 Ubuntu 22.04 LTS must implement NIST FIPS-validated cryptography to protect classified information and for the following: To provision digital signatures, to generate cryptographic hashes, and to protect unclassified information requiring confidentiality and cryptographic protection in accordance with applicable federal laws, Executive Orders, directives, policies, regulations, and standards. prevents CWE-338