Ascensio System SIA OnlyOffice Comment Messages.aspx cross site scripting

published 2025-09-11 13 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-28919

cvss: 3.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 25%
public exploits: 0; none known

A vulnerability was determined in Ascensio System SIA OnlyOffice up to 12.7.0. Impacted is an unknown function of the file /Products/Projects/Messages.aspx of the component Comment Handler. Executing manipulation can lead to cross site scripting. The attack may be launched remotely. The exploit has been publicly disclosed and may be utilized. The vendor was informed early about this issue and replied: "We are already working on this case, and the issues will be resolved in one of the upcoming patches."

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 13 mo ago (2025-09-11)

Exploit prediction

0.33% chance of exploitation in the next 30 days, higher than 25% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

vuldb.com https://vuldb.com/?submit.635871 referenced PoC, tagged "exploit" by a source, unverified
hkohi.ca https://hkohi.ca/vulnerability/21 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	5.1	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
CNA	3.1	3.5	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N/E:P/RL:X/RC:C
CNA	3.0	3.5	CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N/E:P/RL:X/RC:C
CNA	2.0	4.0	AV:N/AC:L/Au:S/C:N/I:P/A:N/E:POC/RL:ND/RC:C
CNA	4.0	2.0	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/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
CNA	3.1	3.5	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N
CNA	2.0	4.0	AV:N/AC:L/Au:S/C:N/I:P/A:N

Affected products

Ascensio System SIA OnlyOffice

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation
CWE-94 Improper Control of Generation of Code

References

vuldb.com /?submit.635871
third-party-advisory, exploit
hkohi.ca /vulnerability/21
exploit
vuldb.com /?id.323615
vdb-entry
vuldb.com /?ctiid.323615
signature, permissions-required

Sources

CVE List CVE-2025-10255
NVD CVE-2025-10255

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary