Is there a patch available for CVE-2026-42336?

Yes, a patch is available for CVE-2026-42336. Update the affected software to the latest version immediately.

MaxKB CVE-2026-42336

Q: What is the CVSS score of CVE-2026-42336?

CVE-2026-42336 has a CVSS 4.0 base score of 5.1 (Medium). CVSS vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.1%.

EUVD-2026-31989 MEDIUM

Time-of-check Time-of-use (TOCTOU) Race Condition (CWE-367)

2026-05-26 GitHub_M

SSRF Maxkb

5.1

CVSS 4.0 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

5.1 MEDIUM

CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector

Network

Attack Complexity

High

Privileges Required

Low

User Interaction

None

Scope

Lifecycle Timeline

Patch available

May 26, 2026 - 22:02 EUVD

Analysis Generated

May 26, 2026 - 21:35 vuln.today

CVSS changed

May 26, 2026 - 21:22 NVD

5.1 (MEDIUM)

CVE Published

May 26, 2026 - 20:22 nvd

UNKNOWN (no severity yet)

DescriptionGitHub Advisory

MaxKB is an open-source AI assistant for enterprise. MaxKB 2.8.0 and prior are vulnerable to a server-side request forgery (SSRF) bypass in the OSS file service URL fetch functionality due to inconsistent DNS resolution between validation and actual request execution, allowing attackers to access internal network services. This vulnerability is fixed in 2.8.1.

AnalysisAI

Authenticated SSRF bypass in MaxKB's OSS file service URL fetch allows low-privilege users to reach internal network services by exploiting inconsistent DNS resolution between validation and request execution. MaxKB 2.8.0 and all prior versions are affected; the attacker causes the validation step to resolve a domain to a public IP, then swaps the DNS record so the actual HTTP fetch resolves to an internal address, bypassing the SSRF filter entirely. No public exploit has been identified and this CVE is not listed in CISA KEV; a vendor-released patch (2.8.1) is available.

Technical ContextAI

MaxKB (CPE: cpe:2.3:a:1panel-dev:maxkb:*:*:*:*:*:*:*:*) is an open-source enterprise AI assistant developed by 1Panel-dev that supports fetching remote URLs as part of its OSS (Object Storage Service) file processing pipeline. The root cause is CWE-367 (Time-of-Check Time-of-Use / TOCTOU Race Condition): the application resolves the attacker-supplied domain hostname once during SSRF validation and a second time during the actual HTTP request, with no guarantee both resolutions return the same IP. An attacker exploits this window by controlling a DNS record with a very short TTL - pointing it to a legitimate public IP during validation to pass the filter, then immediately updating the record to an RFC 1918 or loopback address. When MaxKB performs the real fetch, it re-resolves the hostname and now reaches the internal target. This technique, known as DNS rebinding, is a well-understood class of SSRF bypass enabled specifically by TOCTOU handling in URL validators.

RemediationAI

Vendor-released patch: 2.8.1. Upgrade MaxKB to version 2.8.1 or later as the primary remediation; this version is confirmed by the vendor advisory at https://github.com/1Panel-dev/MaxKB/security/advisories/GHSA-6m4p-9wwc-4q5q. If immediate upgrade is not feasible, restrict access to the OSS URL fetch feature to the most trusted accounts only, reducing the pool of potential abusers - note this may break legitimate use cases for lower-privilege users. As a network-layer control, configure egress firewall rules on the MaxKB host to block outbound connections to RFC 1918 addresses (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) and 169.254.0.0/16 (cloud metadata ranges); this prevents the actual internal fetch even if DNS rebinding succeeds, though it will also block intentional internal integrations. Deploying a DNS resolver with rebinding protection (which rejects DNS responses for public domains that resolve to private IPs) addresses the root cause at the network level but requires infrastructure changes and may affect split-horizon DNS configurations. None of the workarounds fully eliminate the TOCTOU race - patching to 2.8.1 is the only complete fix.