CVE-2026-77991PoC

LOWCVSS 9.4 · CRITICAL

Exploit discussion active in current signal (2 latest mentions)

Immediate actions

Patch affected systems immediately
Hunt for exploitation attempts and persistence artifacts
Increase monitoring for publicly documented tradecraft

Recommended action window: High priority (within 72h)

NVD description

Joomla Extension - joomlaeventmanager.net - Privileged remote code execution in Joomla Event Manager < 5.0.1 - The administrator source model allows to write dangerous file type incl. PHP, leading to remote code execution.

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2.0/ 10 priority

Sources & remediation

Other references

https://www.joomlaeventmanager.net/

Weakness type (CWE)

CWE-434

Priority

LOW

Exploitation

NONE

PoC

YES

Patch

AVAILABLE

Momentum

STABLE

Threat summary

Public PoC is present in monitored signal
Patch or workaround signal is available
3 mentions across 2 observed days
Momentum state: stable

What's happening

PoC mentioned or linked in 2 signals
Patch or workaround mentioned in 1 signal
Technical details provided in 2 signals
Disclosure: 1 classified signal
Peaked at 2 mentions on most recent observed day (2026-09-18)
3 total mentions across 2 days

Deep dive

Activity timeline3 mentions / 2d

Signal classification2 categories

PoC

266.7%

Disclosure

133.3%

Referenced assets3 URLs

By indicator

Classification over time

Date	Total	Labels

2026-08-27	1	Disclosure1
2026-09-18	2	PoC2

Full discourse3 posts

Rıdvan Yağlı@ridvanyagli24d
PoC
🔴 Joomla Event Manager'daki kritik güvenlik açığı CVE-2026-77991 için güvenlik araştırmacısı @abraxas_null tarafından PoC yayınlandı! JEM (Joomla Event Manager) 5.0.0 ve öncesini etkileyen kritik RCE açığında, com_jem bileşenindeki source. save mekanizması kullanılarak normalde CSS dosyalarının yazılması gereken dizine PHP dosyası yazılabiliyor. Yazılan PHP dosyası daha sonra web üzerinden çalıştırılabildiğinden sunucuda uzaktan kod çalıştırma mümkün hale geliyor. Etkilenen sürümler: JEM ≤ 5.0.0 Yamalanan sürüm: 5.0.1 İstismar için yönetici oturumu + core.edit yetkisi gerekiyor. PoC reverse shell içermiyor; PHP dosyasının yazılıp çalıştırılabildiğini witness çıktısıyla gösteriyor. JEM kullanan sistemlerin 5.0.1 veya üzerine mutlaka güncellenmesi gerekiyor. PoC: https://github.com/abraxas/CVE-2026-77991
Post summary
PoC for critical RCE CVE-2026-77991 in Joomla Event Manager (JEM ≤ 5.0.0) published with GitHub link; patched version 5.0.1 available requiring admin + core.edit for exploitation.
03083973
2.4K followersView on X
CERT-PY@CERTpy46d
Disclosure
⚠️ Vulnerabilidad en productos Joomla ❗ CVE-2026-77991 ➡️ Más info: https://www.cert.gov.py/vulnerabilidad-en-productos-joomla-3/ https://t.co/yyU9XyYDvS
Post summary
There is an announcement of a new Joomla vulnerability (CVE‑2026‑77991) with a link to external information, but no further technical, exploit, or mitigation details are supplied.
00010230
6.7K followersView on X
abraxas@abraxas_null24d
PoC
Fresh exploit for all my friends! CVE-2026-77991: Joomla Event Manager, privileged RCE (CRITICAL: 9.4) Exploit: https://abraxaslabs.tech/research/cve-2026-77991 Lab Write-up (with infrastructure): https://abraxaslabs.tech/research/cve-2026-77991 https://t.co/hgiYVLaH4P
Post summary
The tweet announces a Proof of Concept for CVE‑2026‑77991, a critical privileged RCE in Joomla’s Event Manager (CVSS 9.4), and includes links to an exploit and lab write‑up. It highlights the vulnerability’s severity but does not mention patches or active exploitation.
0000078
111 followersView on X

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