CVE-2023-28997 | Nextcloud Desktop: Initialization vector reuse in E2EE allows malicious server admin to break, manipulate, access files

Exp

The Nextcloud Desktop Client is a tool to synchronize files from Nextcloud Server. Starting with version 3.0.0 and prior to version 3.6.5, a malicious server administrator can recover and modify the contents of end-to-end encrypted files. Users should upgrade the Nextcloud Desktop client to 3.6.5 to receive a patch. No known workarounds are available.

Published: 2023-04-04 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-28997 is rated High Exploit Risk (64/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 1.11%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2023-28997

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2023-28997

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.49% 1.11% +0.63%
2 2026-06-14 0.57% 0.49% -0.08%
3 2026-05-28 — 0.57% —

Full EPSS history (47 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-28997

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.7 3.1 MEDIUM
CVSS:3.1/AV:P/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N Click to expand
Attack vector (AV:P)
Hands-on access—USB, keyboard, opening the case—not something you do purely over the wire.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 0.4 5.8 [email protected]
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 1.2 5.2 [email protected]

Weakness enumeration for CVE-2023-28997

OS Trackers for CVE-2023-28997

vendor priority summary link
alpine medium CVE-2023-28997: 1 source package rows (nextcloud-client); 6 state rows across 6 repos (3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 6, open 0. https://security.alpinelinux.org/vuln/CVE-2023-28997
debian not yet assigned CVE-2023-28997 not yet assigned priority: Debian including 1 source packages (nextcloud-desktop), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2023-28997
suse medium — https://www.suse.com/security/cve/CVE-2023-28997/
ubuntu medium CVE-2023-28997 medium priority: Ubuntu including 1 source packages (nextcloud-desktop), 13 status rows across 13 suites (bionic, focal, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 6, ignored 3, needs-triage 2, DNE 1, released 1. https://ubuntu.com/security/CVE-2023-28997

Affected software / configurations for CVE-2023-28997

Vendor Product Version Raw CPE
nextcloud desktop >= 3.0.0, < 3.6.5 cpe:2.3:a:nextcloud:desktop:*:*:*:*:*:*:*:*

References for CVE-2023-28997

cvelogic Threat Intelligence