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01 Record

CVE-2026-103974

lichess.org: Stored HTML Injection via PGN Annotator Tag in Studies

MediumPUBLISHEDCNA: GitHub_M
CNA base score5.4 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

02 Description

lichess.org: Stored HTML Injection via PGN Annotator Tag in Studies

03 Exploitation and scoring

Exploitation
Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.
SSVC decision
  • ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
  • AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
  • Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
0.21% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 11.7% of scored records. A rank, not a probability.
NVD base score
5.4 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
NVD analysis status
Deferred. NVD last modified this record on 2026-10-16.
Red Hat severity
No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2026-10-14 18:17Z14 DAYS AGO
Last updated
2026-10-14 19:41Z14 DAYS AGO
Reserved
2026-10-01
Assigning CNA
GitHub_M
Record state
PUBLISHED
Severity
Medium (CVSS 5.4)
CNA CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Weaknesses
  • CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')Base
Data version
5.2
Document digest
c0fee217841cbfae0c677934efa6dfcb1131d2312ff8d50e7f800126b8e5e42e

05 Affected products

VendorProductVersionsPlatforms
lichess-orglila< c54596c9e1569d378fe20f80d4c790c6fdee54c4—

06 References