CVE-2026-16599 Denial of Service in GNU wget
A malicious FTP server can cause GNU wget to hang by sending a crafted OPIE challenge with a high sequence number, leading to excessive CPU usage.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-16599?
CVE-2026-16599 is a medium-severity denial of service vulnerability in GNU wget, published on 25 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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
Weakness: CWE-606
Which versions are affected by CVE-2026-16599?
Linux distribution packages (10)
wget SUSE:Linux Enterprise Micro 5.5 | All versions | 1.20.3-150000.3.40.1 |
wget SUSE:Linux Enterprise Module for Basesystem 15 SP7 | All versions | 1.24.5-150700.3.12.1 |
wget SUSE:Linux Enterprise Server 16.0 | All versions | 1.25.0-160000.4.1 |
wget SUSE:Linux Enterprise Server LTSS Extended Security 12 SP5 | All versions | 1.14-21.31.1 |
wget SUSE:Linux Enterprise Server for SAP applications 16.0 | All versions | 1.25.0-160000.4.1 |
wget SUSE:Linux Micro 6.0 | All versions | 1.24.5-5.1 |
wget SUSE:Linux Micro 6.1 | All versions | 1.24.5-slfo.1.1_6.1 |
wget SUSE:Linux Micro 6.2 | All versions | 1.25.0-160000.4.1 |
wget openSUSE:Leap 16.0 | All versions | 1.25.0-160000.4.1 |
wget openSUSE:Tumbleweed | All versions | 1.25.0-7.1 |
How do I fix CVE-2026-16599?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-16599 being exploited?
There is no known exploitation of CVE-2026-16599 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-16599, DEBIAN-CVE-2026-16599, ECHO-bd25-6c0f-4704, GHSA-48r3-mr49-jp8x, MGASA-2026-0386, OESA-2026-3766 and 14 more.