01 Record
CVE-2026-42451
Grimmory: Stored XSS via Malicious EPUB Enables Session Token Theft
MediumPUBLISHEDCNA: GitHub_M
CNA base score6.3 CVSS v3.xCVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L
02 Description
Grimmory: Stored XSS via Malicious EPUB Enables Session Token Theft
03 Exploitation and scoring
- Exploitation
- Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
- SSVC decision
- ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
- AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
- Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.
- EPSS probability
- 0.13% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 3.0% of scored records. A rank, not a probability.
- NVD base score
- 6.3 (CVSS v3.x), scored by the NVD independently of the CNA.
- NVD CVSS vector
- CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L
- NVD analysis status
- Deferred. NVD last modified this record on 2026-07-24.
- 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
- 2026-05-08 22:51Z5 MO AGO
- Last updated
- 2026-05-12 18:31Z5 MO AGO
- Reserved
- 2026-04-27
- Assigning CNA
- GitHub_M
- Record state
- PUBLISHED
- Severity
- Medium (CVSS 6.3)
- CNA CVSS vector
- CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L
- Weaknesses
- Data version
- 5.2
- Document digest
- 9c0e374f8164ce340d36745026f8b613f474e260b3b9b58cfed8162fbcb36fc7
05 Affected products
VendorProductVersionsPlatforms