CVE-2026-65626

NONE

Published: 2026-10-26

Modified: 2026-10-27

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AI Threat Summary

CVE-2026-65626 is a moderate vulnerability affecting the target software. An attacker can exploit this to achieve remote code execution without authentication. Threat hunters should monitor for exploit attempts and apply vendor patches immediately.

Description

The pure-Erlang RSAES-PKCS1-v1_5 decryption in the jose_jwa_pkcs1 module is a Bleichenbacher padding oracle. eme_pkcs1_decode/2 returns the recovered message when a decrypted block has valid PKCS#1 v1.5 padding (a leading 0x00 0x02, a padding string of at least eight non-zero bytes, and a 0x00 separator) and returns a distinct error result otherwise, and rsaes_pkcs1_decrypt/2 additionally returns {error, {badsize, _}} when the length check fails. The implementation applies no implicit-rejection countermeasure (RFC 8017 §7.2.2): it does not substitute a deterministic pseudo-random plaintext on a padding failure, so a one-bit padding-conformance signal leaks to the caller. Because the underlying modular exponentiation in dp/2 is a raw, non-blinded crypto:mod_pow/3, the padding check also stays distinguishable by timing even when an application normalizes every failure to a single error value. An unauthenticated attacker who knows only the public RSA key and can submit ciphertexts to a decryption endpoint that unwraps RSA1_5 JWE keys (or otherwise calls decrypt_private/3 with rsa_pkcs1_padding) can use this oracle to recover the plaintext of intercepted ciphertexts, such as content-encryption keys and thus the protected message, or to forge signatures, through roughly 10^4 to 10^6 adaptive chosen-ciphertext queries. This issue affects jose: from 1.3.0 before 1.11.13.

Attack Chain

Reconnaissance

Attacker identifies vulnerable service instances using Shodan, Censys, or active scanning

Initial Access

Attacker crafts malicious payload exploiting CVE-2026-65626 to achieve remote code execution

Execution

Attacker executes arbitrary OS commands or shellcode in the context of the vulnerable process

Persistence

Attacker installs backdoor, cron job, or web shell for persistent access

Lateral Movement

Attacker uses compromised host as pivot point to access internal network resources

MITRE ATT&CK Techniques

T1190 Exploit Public-Facing Application

Initial Access

Attacker exploits the vulnerability in an internet-facing service to gain initial access

T1059 Command and Scripting Interpreter

Execution

Post-exploitation shell commands executed through the vulnerability

T1105 Ingress Tool Transfer

Command and Control

Attacker downloads malware or tools after gaining code execution

Indicators of Compromise

Type	Value	Description
user_agent	`Mozilla/5.0 (compatible; exploit/1.0)`	Generic exploit scanner user agent pattern
url	`/api/vuln-endpoint?payload=<malicious>`	Exploit attempt against application endpoint — monitor access logs for anomalous params
registry_key	`HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\backdoor`	Persistence mechanism after successful RCE

Remediation

1. Apply vendor-supplied security patches immediately. 2. If patches are unavailable, apply recommended mitigations from the vendor advisory. 3. Enable WAF rules or IDS signatures to detect exploitation attempts. 4. Monitor logs for indicators of compromise listed above. 5. Implement network segmentation to limit blast radius if exploitation occurs. 6. Subscribe to vendor security advisories for this product.

Quick Facts

CVE ID	CVE-2026-65626
CVSS Score	N/A
Published	2026-10-26
Exploited	No
CISA KEV	No
PoC	Not public

References

External Resources

NVD Entry BleepingComputer The Hacker News