9.8

CVE-2025-66277: qnap systems inc. qts Link Following

CVSS: 9.8v3.1CriticalAnalyzed
Published 11-02-2026Last modified 26-02-2026
Open JSON

Vulnerability summary

CVE-2025-66277 is a critical (CVSS 9.8) Link Following vulnerability in qnap systems inc. qts. EPSS estimates a 0.71% chance of exploitation in the next 30 days, higher than 53% of scored vulnerabilities.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.8/10
010
Critical · v3.1 (NVD)
EPSS score
0.71%
0%100%
Low · +0.06 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 11-02-2026
    PublishedVulnerability first disclosed.
  2. 26-02-2026
    Last modifiedVulnerability information updated.

Description

A link following vulnerability has been reported to affect several QNAP operating system versions. The remote attackers can then exploit the vulnerability to traverse the file system to unintended locations. We have already fixed the vulnerability in the following versions: QTS 5.2.8.3350 build 20251216 and later QuTS hero h5.3.2.3354 build 20251225 and later QuTS hero h5.2.8.3350 build 20251216 and later

CVSS metrics

3 scores · 2 sources · 2 versions

EPSS trend

Probability

0.71%

Chance of exploitation in the next 30 days

Percentile

53%

Versus all other CVEs

30-day change

+0.06 pp

From 0.66% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.71%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Qnap2 products
  • qts5.2.0.2737:build_20240417 | 5.2.0.2744:build_20240424 | 5.2.0.2782:build_20240601 | 5.2.0.2802:build_20240620 | 5.2.0.2823:build_20240711 | 5.2.0.2851:build_20240808 | 5.2.0.2860:build_20240817 | 5.2.1.2930:build_20241025 | 5.2.2.2950:build_20241114 | 5.2.3.3006:build_20250108 | 5.2.4.3070:build_20250312 | 5.2.4.3079:build_20250321 | 5.2.4.3092:build_20250403 | 5.2.5.3145:build_20250526 | 5.2.6.3195:build_20250715 | 5.2.6.3229:build_20250818 | 5.2.7.3256:build_20250913 | 5.2.7.3297:build_20251024 | 5.2.8.3332:build_20251128
  • quts_heroh5.2.0.2737:build_20240417 | h5.2.0.2782:build_20240601 | h5.2.0.2789:build_20240607 | h5.2.0.2802:build_20240620 | h5.2.0.2823:build_20240711 | h5.2.0.2851:build_20240808 | h5.2.0.2860:build_20240817 | h5.2.1.2929:build_20241025 | h5.2.1.2940:build_20241105 | h5.2.2.2952:build_20241116 | h5.2.3.3006:build_20250108 | h5.2.4.3070:build_20250312 | h5.2.4.3079:build_20250321 | h5.2.5.3138:build_20250519 | h5.2.6.3195:build_20250715 | h5.2.7.3256:build_20250913 | h5.2.7.3297:build_20251024 | h5.2.8.3321:build_20251117
Qnap systems inc.2 products
  • qts≥ 5.2.x, < 5.2.8.3350 build 20251216
  • quts hero≥ h5.3.x, < h5.3.2.3354 build 20251225 | ≥ h5.2.x, < h5.2.8.3350 build 20251216

2 vendors · 4 products

References

1 links