CVE-2026-99059

HIGH CVSS 7.7 PoC Available
Published: 2026-10-23
Modified: 2026-10-24
Enriched via mock
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AI Threat Summary

CVE-2026-99059 is a high-severity vulnerability with a CVSS score of 7.7 affecting the target software. Threat hunters should monitor for exploit attempts and apply vendor patches immediately.

Description

In the Linux kernel, the following vulnerability has been resolved: wireguard: noise: reject response consumption after intermediate initiation Two threads begin processing the identical response message, received twice. The first thread, A, runs. While it's running, the second one, B, gets partway through, and during that slow calculation, or even while blocking on down_write(), A completes and then also a handshake initiation that's already been queued up runs in thread C, which itself takes that same down_write(). The handshake initiation creation succeeds, and sets the state back to waiting-for-response, and calls up_write(), at which point thread B resumes, because either its finished its calculations or was finally allowed to acquire down_write(). Thread B then copies the state back to the peer, and begins a new session, using that state, which is the same session as the one made in thread A. Thread A Thread B Thread C down_read() sA = handshake->state memcpy(cA, handshake->crypto) up_read() if (sA != 1) goto fail slow_crypto(cA) down_read() sB = handshake->state memcpy(cB, handshake->crypto) up_read() if (sB != 1) goto fail slow_crypto(cB) down_write() if (sA != handshake->state) goto fail memcpy(handshake->crypto, cA) handshake->state = 2 up_write() down_write() if (handshake->state != 2) goto fail derive_session(handshake->crypto) up_write() down_write() slow_crypto(handshake->crypto) handshake->state = 1 up_write() down_write() if (sB != handshake->state) goto fail memcpy(handshake->crypto, cB) handshake->state = 2 up_write() down_write() if (handshake->state != 2) goto fail derive_session(handshake->crypto) up_write() This seems basically impossible to hit in a meaningful way in practice, but ensure that it absolutely cannot happen by comparing the ephemeral private key that's on the stack with the latest one that the peer's handshake state has.

Attack Chain
1
Reconnaissance

Attacker scans for vulnerable versions using version banners or PoC scanners

2
Initial Access

Attacker triggers CVE-2026-99059 vulnerability with a crafted request or payload

3
Execution

Vulnerability exploited to perform unauthorized actions on the target system

4
Impact

Depending on vulnerability type, attacker achieves data access, service disruption, or code execution

MITRE ATT&CK Techniques
T1190 Exploit Public-Facing Application
Initial Access

Public-facing application vulnerability exploited for initial access

T1203 Exploitation for Client Execution
Execution

Vulnerability exploited to execute attacker-controlled code

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
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-2026-99059
CVSS Score 7.7
Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L
Published 2026-10-23
Exploited No
CISA KEV No
PoC Available
References
External Resources
NVD Entry BleepingComputer The Hacker News