CVE-2023-45239
Facebook Tac Plus ≤ 2023-10-05
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2023-45239 is a critical-severity Improper Filtering of Special Elements (CWE-790) vulnerability in Facebook Tac Plus. Its CVSS base score is 9.8 (Critical).
Operationally, ranked in the top 17% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
A lack of input validation in tac_plus prior to commit 4fdf178 permits command injection when pre-auth or post-auth commands are enabled. The affected component is the Facebook-maintained tac_plus TACACS+ server, which processes untrusted values for username, rem-addr, and NAC address fields without sanitization.
An unauthenticated network attacker who can influence any of those three fields can inject arbitrary shell commands and obtain remote code execution on the tac_plus server. The vulnerability carries a CVSS 3.1 score of 9.8, reflecting network-accessible exploitation with no required credentials or user interaction.
Advisories published with the GitHub security notice GHSA-p334-5r3g-4vx3 and the associated pull request recommend upgrading to a build that includes commit 4fdf178; downstream distributions such as Fedora have issued corresponding package updates that apply the same fix.
EPSS for the CVE rose from a low baseline to a peak of 0.3589, indicating increased exploitation interest after public disclosure.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-49545
Vulnerability Data
A lack of input validation exists in tac_plus prior to commit 4fdf178 which, when pre or post auth commands are enabled, allows an attacker who can control the username, rem-addr, or NAC address sent to tac_plus to inject shell commands…
more
and gain remote code execution on the tac_plus server.
- CWE(s)
Related Threats
CVEs Like This One
Affected Assets
Mitigating Controls
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.
A.8.25 mandates secure SDLC practices including secure coding guidelines, security requirements, checkpoints, testing (scans/penetration), and developer training that reach improper filtering of special elements, but leaves a bounded remainder (e.g. incomplete enforcement across all languages, second-order filtering, or outsourced development without full assurance).
A.8.26 requires identifying and specifying requirements (including resilience against SQL injections, input validation, and output controls) that can stop exploitation of improper filtering, but does not itself implement or enforce those filters.
A.8.27 mandates security-by-design principles (including distrust external input, data validation/sanitization, defense-in-depth, and secure architecture reviews against attack patterns), which reaches a minority slice of CWE-790 by guiding developers to filter special elements before downstream use; most instances arise from incomplete or missing implementation of those principles.
Secure coding standards require proper filtering and encoding of special elements before downstream processing.
Security testing can detect improper filtering but does not itself implement the filtering control.
Hardening callouts derived
DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.
- No fine-grained STIG row for CWE-790, a class-level weakness, and none of its children carries one either.