Answer in brief
CVE-2025-26466 records a Medium severity (CVSS 5.9) vulnerability in Openssh: denial-of-service in openssh. The current sources do not mark it as known exploited. The current feed maps Red Hat/openssh (generic), OpenSSH (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.9. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Red Hat/openssh (generic), OpenSSH (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:a:openbsd:openssh:9.5:p1:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:a:openbsd:openssh:9.6:-:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:a:openbsd:openssh:9.6:p1:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:a:openbsd:openssh:9.7:-:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:a:openbsd:openssh:9.7:p1:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:a:openbsd:openssh:9.8:-:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:a:openbsd:openssh:9.8:p1:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:a:openbsd:openssh:9.9:-:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:a:openbsd:openssh:9.9:p1:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:canonical:ubuntu_linux:24.04:*:*:*:lts:*:*:* | Not reported | Not reported |
| cpe:2.3:o:canonical:ubuntu_linux:24.10:*:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:debian:debian_linux:12.0:*:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:debian:debian_linux:13.0:*:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| Red Hat/opensshgeneric | * | Not reported |
| OpenSSHgeneric | >=9.5p1 <=9.9p1 | Not reported |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.0 <V3.1.5 | V3.1.5 |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.0 <V3.1.5 | V3.1.5 |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.0 <V3.1.5 | V3.1.5 |
Published upstream
Feb 28, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 21, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jun 25, 2026
A flaw was found in the OpenSSH package. For each ping packet the SSH server receives, a pong packet is allocated in a memory buffer and stored in a queue of packages. It is only freed when the server/client key exchange has finished. A malicious client may keep sending such packages, leading to an uncontrolled increase in memory consumption on the server side. Consequently, the server may become unavailable, resulting in a denial of service attack.
Quoted source text, attributed separately from HOL analysis.