# CVE-2026-16599

## Summary

- **CVE ID:** CVE-2026-16599
- **Severity:** MEDIUM
- **CVSS Score:** 5.1 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N)
- **CWE:** CWE-606
- **Published:** Aug 25, 2026
- **Last Modified:** Aug 25, 2026

## Description

GNU wget is vulnerable to denial of service in its FTP OPIE/S-KEY authentication functionality. The server-supplied sequence number from the FTP challenge line is used as an iteration count for an MD5 key-derivation loop without any upper bound validation. A malicious FTP server or a network attacker positioned to intercept FTP traffic can send a crafted OPIE challenge with a sequence number near INT_MAX, causing wget to perform up to approximately 2.1 billion MD5 computations and suspend for some time. The --timeout option does not mitigate this because it applies only to network I/O, not CPU computation.


This issue was fixed in commit e9697d98e7249b0f68a6be040a4f3dcc5bc101fa

## Affected Products

- GNU — wget (0)

## References

- [CNA](https://cert.pl/en/posts/2026/08/CVE-2026-16599)
- [CNA](https://gitlab.com/gnuwget/wget)
- [CNA](https://gitlab.com/gnuwget/wget/-/commit/e9697d98e7249b0f68a6be040a4f3dcc5bc101fa)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.38%
- **EPSS Percentile:** 31.3

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._