CVE-2026-78221: openvpn Incorrect Calculation of Buffer Size
CVSS: 5.9v4.0MediumAwaiting analysis
AliasesUBUNTU-CVE-2026-78221
Published 07-09-2026Last modified 08-09-2026
Vulnerability summary
CVE-2026-78221 is a medium (CVSS 5.9) Incorrect Calculation of Buffer Size vulnerability in openvpn. EPSS estimates a 0.12% chance of exploitation in the next 30 days, higher than 1.5% of scored vulnerabilities.
CVSS score
5.9/10
010
Medium · v4.0 (CVE.org)EPSS score
0.12%
0%100%
Low · 0.00 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Timeline
- 07-09-2026PublishedVulnerability first disclosed.
- 08-09-2026Last modifiedVulnerability information updated.
Description
An incorrect buffer size calculation in the Windows Interactive Service in OpenVPN 2.7_alpha1 through 2.7.6 allows local authenticated users to cause memory corruption or disclose sensitive information via crafted NRPT inputs.
CVSS metrics
3 scores · 3 sources · 1 versionMedium 5.9Preferred score · CVE.org (CNA)
CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:P/VC:H/VI:N/VA:H/SC:H/SI:N/SA:HSourcesAll 3 agree
- OSV · UbuntuEcosystem advisory · calculated5.9MediumCVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:P/VC:H/VI:N/VA:H/SC:H/SI:N/SA:H
- NVDNIST5.9MediumCVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:P/VC:H/VI:N/VA:H/SC:H/SI:N/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS trend
Probability
0.12%
Chance of exploitation in the next 30 days
Percentile
2%
Versus all other CVEs
30-day change
0.00 pp
From 0.12% on 21-09-2026
21-09-202621-10-2026
EPSS score0.12%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Openvpn1 product
- openvpn≥ 2.7_alpha1, ≤ 2.7.6
Ubuntu1 product
- openvpnAll versions (No fix recorded)
2 vendors · 2 products