High

Information Disclosure via Error Messages in QNAP HBS 3 Hybrid Backup Sync

IdentifiersCVE-2025-62840CWE-209· Generation of Error Message…

CVE-2025-62840 is an information disclosure vulnerability in QNAP HBS 3 Hybrid Backup Sync affecting versions prior to 26.2.0.938. The flaw is described by QNAP as generation of error messages containing sensitive information. Supporting disclosure context indicates the issue exists in handling of the rr2s.kwargs parameter by the server_handlers.pyc endpoint, where error output can expose sensitive application data. On affected QNAP TS-453E installations, a network-adjacent attacker can trigger the vulnerable error-handling path and obtain information that should not be disclosed. Although exploitation is described as requiring authentication, the associated advisory context also states the authentication mechanism can be bypassed.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows disclosure of sensitive information and application data from the affected HBS 3 component. The direct impact is confidentiality loss rather than integrity or availability impact. Advisory context further notes that the exposed information may be useful in chaining with other vulnerabilities, and that this issue could be combined with additional flaws to facilitate arbitrary code execution in the context of the RR2 administrator.

Mitigation

If you can’t patch tonight, do this now.

Until patches can be deployed, restrict access to HBS 3 and related management interfaces to trusted hosts only. Limit exposure to the local network, enforce network segmentation, firewall or ACL restrictions, and prefer VPN-only administrative access. Reduce network-adjacent reachability to affected NAS services and monitor for abnormal requests to the server_handlers.pyc endpoint, particularly involving rr2s.kwargs-triggered error conditions.

Remediation

Patch, then assume compromise.

Upgrade QNAP HBS 3 Hybrid Backup Sync to version 26.2.0.938 or later. QNAP indicates the vulnerability is fixed in HBS 3 Hybrid Backup Sync 26.2.0.938 and later, and remediation details were published in QNAP advisory QSA-25-46. QNAP also recommended changing all passwords after applying the update.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

QNAP SystemsHbs 3 Hybrid Backup Syncapplication

QNAP SystemsHybrid Backup Syncapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

9 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

9 SOURCESView more in app

security affairsNews

Mar 23, 2026

QNAP fixed four vulnerabilities demonstrated at Pwn2Own Ireland 2025

A QNAP vulnerability affecting HBS 3 Hybrid Backup Sync, referenced as one of the zero-day vulnerabilities patched after Pwn2Own Ireland 2025.

securityaffairsNews

Nov 10, 2025

QNAP fixed multiple zero-days in its software demonstrated at Pwn2Own 2025

A zero-day vulnerability in QNAP HBS 3 Hybrid Backup Sync software, demonstrated at Pwn2Own 2025 and patched by QNAP.

bleeping computerNews

Nov 7, 2025

QNAP fixes seven NAS zero-day flaws exploited at Pwn2Own

A zero-day vulnerability in QNAP's HBS 3 Hybrid Backup Sync, exploited during Pwn2Own Ireland 2025.

security weekNews

Mar 18, 2026

QNAP Patches Vulnerabilities Exploited at Pwn2Own Ireland

One of multiple vulnerabilities demonstrated at Pwn2Own Ireland 2025 affecting QNAP routers and NAS devices; patched by QNAP (via HBS 3 Hybrid Backup Sync update).

What this page doesn’t show

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Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity4