Vulnerability · Published Mar 12, 2026 · Assigned by CERT-PL
CVE-2026-0809Weak KSeF token encoding in Streamsoft Prestiż
Medium 6.3
In plain English
A medium-severity security flaw in Streamsoft Prestiż from Streamsoft. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 18% of all known vulnerabilities).
Severity (CVSS 4.0)6.3Medium
Exploit odds (30 days)0.3%top 81.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Use of a custom token encoding algorithm in Streamsoft Prestiż software allows the value of the KSeF (Krajowy System e-Faktur) token to be guessed after analyzing how tokens with know values are encoded. This issue was fixed in version 20.0.380.92.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Streamsoft | Streamsoft Prestiż | 12.2.363.17 – before 20.0.380.92 |
Weakness: CWE-261 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
References
- https://www.streamsoft.pl/streamsoft-prestiz/ product
- https://cert.pl/posts/2026/03/CVE-2026-0809 third-party-advisory