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Fencer Intel
high 8.8

CVE-2025-26210 json

DeepSeek R1 through V3.1 allows XSS, as demonstrated by JavaScript execution in the context of the run-html-chat.deepseeksvc.com domain.

published last yr. modified 4mo ago also EUVD-2025-26507

cvss
8.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 49%
public exploits
0
none known

Summary

DeepSeek R1 through V3.1 allows XSS, as demonstrated by JavaScript execution in the context of the run-html-chat.deepseeksvc.com domain. NOTE: some third parties have indicated that this is intended behavior.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
last yr.

Exploit prediction

0.60% chance of exploitation in the next 30 days, higher than 49% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • hackmd.io https://hackmd.io/@MrqrFIlhQFi7vUwkqbrXDw/deepseek referenced PoC, tagged "exploit" by a source, unverified
  • youtu.be https://youtu.be/IgQwy52FVT4 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CNA 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Intel 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.