Security readout for executives and security teams
Plain-English summary
CVE-2026-22813 affects OpenCode, an open source AI coding agent. A crafted LLM response can inject HTML/JavaScript into the local web UI and run in the localhost OpenCode origin. The advisory says this can lead to command execution on the local system. OpenCode versions before 1.1.10 are affected.
Executive priority
Treat as urgent for teams using OpenCode. The vulnerability is critical, affects developer endpoints, and the advisory states possible local command execution. Prioritize upgrade to 1.1.10, then confirm coverage across engineering workstations.
Technical view
The issue is CWE-79 XSS in OpenCode’s markdown renderer for LLM responses. It inserts arbitrary HTML into the DOM without DOMPurify-style sanitization or a Content Security Policy. An attacker who controls a chat response can execute JavaScript on http://localhost:4096. CVSS v4.0 score is 9.4. Fixed version: 1.1.10.
Likely exposure
Systems running anomalyco OpenCode below 1.1.10 are exposed, especially where users interact with untrusted prompts, model outputs, repositories, or websites that can influence a chat session. The vulnerable service is described as the local web UI on localhost:4096.
Exploitation context
The source describes user interaction as required and exploitation through controlled LLM response content rendered in the web UI. No cited source or KEV entry indicates active exploitation in the wild. Public evidence is limited to the CVE record and GitHub advisory.
Researcher notes
The public description does not provide full exploit mechanics beyond unsafe HTML rendering of LLM responses and JavaScript execution on localhost:4096. Avoid assuming broader network exposure or active exploitation without additional evidence. Key validation is version-based because the fixed release is explicitly named.
Mitigation direction
- Upgrade OpenCode to version 1.1.10 or later.
- Identify and prioritize developer workstations running OpenCode before 1.1.10.
- Review vendor advisory for any additional hardening guidance.
- Limit interaction with untrusted content until upgraded.
Validation and detection
- Check installed OpenCode version on developer systems.
- Confirm affected installations are below 1.1.10.
- Verify upgraded systems report OpenCode 1.1.10 or later.
- Review local OpenCode usage where untrusted LLM responses were rendered.
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-2026-22813 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
- Critical
- CVSS
- 9.4 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
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.
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:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H——Primary CVE scoreVulnerability scoring details
Base CVSS 4.0 score
9.4CriticalVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/anomalyco/opencode/security/advisories/GHSA-c83v-7274-4vgpCVE reference · x_refsource_CONFIRM
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.