CVE-2025-64764 — Astro is vulnerable to Reflected XSS via the server islands feature
Astro is a web framework. Prior to version 5.15.8, a reflected XSS vulnerability is present when the server islands feature is used in the targeted application, regardless of what was intended by the component template(s). This issue has been patched in version 5.15.8.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- Public exploit/PoC (nuclei)+4
- EPSS 0.5% (30-day exploitation probability)+6
- Technical severity (medium)+3
- CISA SSVC: exploitation "poc"+5
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
- Documented patch — github.com (NIST National Vulnerability Database)
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Astro Astro, Withastro Astro).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- Apply the fixed version or the patch documented under Remediation.
- Exploitation requires user interaction: tighten email/web filtering and warn affected users.
- Search available logs for exploit probes, errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 7.1 | CVSS 3.1 | High | 2.8 | 4.2 | security-advisories@github.com via NIST National Vulnerability Database |
| 7.1 | CVSS 3.1 | High | — | — | GitHub_M via CVE Program (cve.org) e CISA ADP |
| 5.4 | CVSS 3.1 | Medium | 2.8 | 2.5 | nvd@nist.gov via NIST National Vulnerability Database |
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N (score shown at the top: nvd@nist.gov) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
Public exploits, PoCs and detection templates
Public code that demonstrates or tests the flaw raises the odds of mass exploitation — and Nuclei templates help find vulnerable assets in your environment.
Warning: public PoCs are sometimes disguised malware. Use them only for authorized testing in an isolated environment. This portal does not host exploit code — it only points to the sources.
EPSS over time FIRST
Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.49%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · withastro/astro
- SSVC assessment updated
- Record published
- Fix documented
- CVSS changed · 5.4
- Source status changed · → Analyzed
- Record created in this database
- 2025
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
2 on the record
Elsewhere on this site
Related CVEs (same products)
- Low CVE-2026-59730 @astrojs/node: Backslash-prefixed paths not recognized as internal by trailing-slash redirect Jul 27, 2026
- Medium CVE-2026-59728 @astrojs/rss: XML Injection via Unescaped RSS Feed Fields Jul 27, 2026
- Low CVE-2026-59727 Astro: Cross-site scripting via unescaped transition:* directive values on hydrated islands Jul 27, 2026
- Medium CVE-2026-59729 Astro: XSS via unescaped spread attribute names in renderHTMLElement (incomplete fix for CVE-2026-54298) Jul 27, 2026
- High CVE-2026-59731 Astro 6.4.7 Authorization Bypass via Decode Iteration Limit and Rewrite Path Canonicalization Mismatch Jul 8, 2026
- Medium CVE-2026-54298 Astro: XSS via Unescaped Attribute Names in Spread Props Jun 22, 2026
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2025-64764 is "Astro is vulnerable to Reflected XSS via the server islands feature", rated Medium. It affects Astro (Astro); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.4 describes technical severity. EPSS 0.49% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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