Security readout for executives and security teams
Plain-English summary
CVE-2025-51857 is a cross-site scripting issue in Halo system version 2.20.18LTS and earlier. An attacker could cause script to run in a user’s browser if that user interacts with malicious content. The published severity is medium, with limited confidentiality and integrity impact and no availability impact indicated.
Executive priority
Treat as a near-term remediation item for internet-facing or broadly used Halo deployments. The issue is not currently evidenced as exploited in the provided sources, but XSS can support account abuse, data exposure, and unauthorized actions under victim context.
Technical view
The CVE describes CWE-79 XSS in the reconcile method of the AttachmentReconciler class in Halo. CVSS 3.1 is 6.1: network exploitable, low complexity, no privileges required, user interaction required, changed scope, low confidentiality and integrity impact, and no availability impact.
Likely exposure
Organizations running Halo system v2.20.18LTS or earlier may be exposed. The CVE record does not provide CPEs, deployment assumptions, or a confirmed fixed version.
Exploitation context
The CVE is not listed as KEV, and the provided sources do not state active exploitation. Successful exploitation requires user interaction, consistent with reflected or stored XSS-style browser execution risk.
Researcher notes
Public data is sparse. The CVE names the vulnerable class and method but does not include official affected CPEs, a vendor advisory, or a fixed version. Avoid assuming exploit maturity beyond the CVSS characteristics and referenced materials.
Mitigation direction
- Inventory Halo deployments and identify versions at or below 2.20.18LTS.
- Review Halo project advisories, releases, and issue guidance for an official fix.
- Apply vendor-recommended updates or configuration changes when available.
- Limit exposure of administrative or content-management interfaces where practical.
- Educate users not to interact with untrusted attachment-related content.
Validation and detection
- Confirm whether Halo is present in the environment.
- Record the exact Halo version for each instance.
- Review application logs for suspicious attachment-related activity.
- Check vendor sources for a patched version or advisory.
- Validate remediation in a non-production environment first.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2025-51857 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N2.82.7CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
6.1MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/halo-dev/haloCVE reference, mitre
- https://gist.github.com/this1slwl/d714514635119159607c14faebbbcf20CVE reference, mitre
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.