CVE-2026-56389 — CVE & Security Advisory Radar

🎯 CVE-2026-56389 MEDIUM 6.8 🔥 EPSS 15% 🇪🇺 EUVD

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CVE-2026-56389 | GNU Bison allows for an execution of an arbitrary program during HTML report generation due to improper handling of grammar-defined configuration variables. A grammar file can override the executable used for the XML‑to‑HTML transformation step via %define tool.xsltproc, which is accepted without restriction and passed directly to execvp(). When running bison --html on a attacker-provided grammar, this behavior allows execution of an arbitrary program with

GNU Bison allows for an execution of an arbitrary program during HTML report generation due to improper handling of grammar-defined configuration variables. A grammar file can override the executable used for the XML‑to‑HTML transformation step via %define tool.xsltproc, which is accepted without restriction and passed directly to execvp().

When running bison --html on a attacker-provided grammar, this behavior allows execution of an arbitrary program with the privileges of the Bison process.

Maintainers of this project were notified about this vulnerability, and fixed the issue in commit 3169c1e7a2c6acc4c59dfcf8b089896d6881925b. However, they did not provide vulnerable version range. Version 3.8.2 was tested and confirmed as vulnerable, other versions were not tested but might also be vulnerable.

Klassifikation & Betroffenheit:

GNU Bison 3.8.2gnu bison 3.8.2

Improper Control of Generation of Code ('Code Injection') 🎯 Medium

The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.

🛡️ Empfohlene Mitigation: Refactor your program so that you do not have to dynamically generate code.

Vollständige Definition bei MITRE ➔

⚔️ Typische Angriffsmuster (CAPEC):

CAPEC-35 · Leverage Executable Code in Non-Executab… (Very High) CAPEC-77 · Manipulating User-Controlled Variables (Very High) CAPEC-242 · Code Injection (High)

🎯 ATT&CK-Techniken (Kill-Chain-Verhalten):

T1027.006 · Obfuscated Files or Information: H… T1027.009 · Obfuscated Files or Information: E… T1564.009 · Hide Artifacts: Resource Forking

🧩 Ähnliche Schwachstellen (Hersteller/Klasse/Score-Band):

CVE-2025-61662 7.8 CVE-2026-48829 7.5 CVE-2026-28372 7.4 CVE-2025-69720 7.3 CVE-2026-77219 6.9

📚 Referenzen & Quellen:

🇪🇺 Original-Eintrag (ENISA EUVD) 🇺🇸 NVD-Eintrag

Ausnutzungs-Zeitleiste:

Reserviert 2026

Veröffentlicht 07/2026

Heute 03.09.

CVSS-Vektor-Analyse: 6.8

AV · Angriffsvektor Lokal

AC · Komplexität Gering

PR · Privilegien Keine

CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:L/SC:L/SI:L/SA:L

Veröffentlicht:29.07.2026

Aktualisiert:24.08.2026 16:18

Assigner (CNA):CERT-PL

EUVD-ID:EUVD-2026-50276

Quellen: 🇪🇺 EUVD-Datenbank (ENISA) + 🇺🇸 NVD-Anreicherung · 24-h-Cache

CWE-94: Code Injection ✓ Offizieller Patch / Advisory verfügbar

💡 Gegenmaßnahme: Sicherheits-Update des Herstellers zeitnah einspielen und Netzwerksegmentierung prüfen.

Tier	2026-08-29	2026-09-02
≥90 %	4	0
≥50 %	4	0
≥10 %	3	0
<10 %	304	300

Datenquellen & Methodik: Primärquelle ist die EUVD der ENISA (laufender Datenbank-Sync, alle 15 Minuten), abgeglichen mit dem CISA-KEV-Katalog und der NVD — Detail-Dossiers reichern fehlende Felder live per NVD an — mit Fallback auf CIRCL vulnerability-lookup (EU/Non-Profit, aggregiert CVE-, GitHub- und OSV-Advisories). Der CISA-KEV-Katalog (Known Exploited Vulnerabilities, ~1.700 aktiv ausgenutzte Schwachstellen) wird bei jedem Sync vollständig neu geladen und kreuzreferenziert — filterbar über die KEV-Pille. CVSS 3.1 wird nach Ampel-Logik aus Verteidigersicht dekodiert; EPSS bezeichnet die 30-Tage-Exploit-Wahrscheinlichkeit (FIRST.org).

🇪🇺 ENISA EUVD 🇺🇸 NVD ⚠️ CISA KEV ⚡ EPSS

6.8 MEDIUM

🇪🇺 EUVD

EPSS

15%

CVE-2026-56389 💻 Lokal 🔓 Keine Authentifizierung nötig

GNU

CVE-2026-56389 | GNU Bison allows for an execution of an arbitrary program during HTML report generation due to improper handling of grammar-defined configuration variables. A grammar file can override the executable used for the XML‑to‑HTML transformation step via %define tool.xsltproc, which is accepted without restriction and passed directly to execvp(). When running bison --html on a attacker-provided grammar, this behavior allows execution of an arbitrary program with

CWE-94: Code Injection ✓ Offizieller Patch / Advisory verfügbar

💡 Gegenmaßnahme: Sicherheits-Update des Herstellers zeitnah einspielen und Netzwerksegmentierung prüfen.

29.07.2026

🛡️ Details ➔

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