Security readout for executives and security teams
Plain-English summary
Astro applications before 9.5.4 can be tricked into making server-side requests when rendering certain error pages. In the right deployment, an attacker may read responses from internal services, including cloud metadata endpoints. The issue requires specific conditions, so urgency is moderate but real for exposed Astro SSR deployments.
Executive priority
Prioritize remediation for internet-facing Astro SSR applications, especially cloud-hosted origins. The business risk is unauthorized reading of internal service responses under specific conditions. Upgrade during the next urgent maintenance window, faster for exposed production systems.
Technical view
CVE-2026-25545 is a CWE-918 SSRF in Astro before 9.5.4. Server-side rendered pages that return errors with prerendered custom error pages can trust a manipulated Host header, fetch an attacker-controlled /500.html, and follow redirects to internal URLs. Version 9.5.4 fixes the issue.
Likely exposure
Exposure is most likely for Astro SSR applications below 9.5.4 using prerendered custom error pages such as 404.astro or 500.astro, where the origin server is directly reachable or Host header validation is absent. Strong proxy enforcement may reduce exposure.
Exploitation context
The CVSS 4.0 score is 6.9 with network access, no privileges, no user interaction, high attack complexity, and prerequisites. Sources do not report active exploitation, and the CVE is not listed as KEV in the provided bundle.
Researcher notes
Focus review on Astro error rendering paths and deployments that allow untrusted Host headers to influence server-side fetch behavior. The public sources identify the fix commit and 9.5.4 release but do not provide evidence of exploitation in the wild.
Mitigation direction
- Upgrade affected Astro deployments to version 9.5.4 or later.
- Review the GitHub advisory and release notes for vendor guidance.
- Ensure Host headers are validated at the proxy or application boundary.
- Prevent direct public access to origin servers behind proxies.
- Review cloud metadata and internal service access controls.
Validation and detection
- Inventory Astro applications and confirm installed versions.
- Identify SSR deployments using prerendered custom error pages.
- Check whether origins are directly reachable from the internet.
- Verify proxy or application Host header validation is enforced.
- Confirm remediation by verifying Astro is 9.5.4 or later.
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-918: Information exposure and cloud metadata lookup
Information exposure and SSRF weaknesses can make discovery, cloud metadata, and credential material review relevant. 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 lookupCloud metadata behavior lookup
The CVE wording references SSRF or metadata access, so cloud discovery and credential material review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-25545 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
- 6.9 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA: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.
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:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N——Primary CVE scoreVulnerability scoring details
Base CVSS 4.0 score
6.9MediumVector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/withastro/astro/security/advisories/GHSA-qq67-mvv5-fw3gCVE reference · x_refsource_CONFIRM
- https://github.com/withastro/astro/commit/e01e98b063e90d274c42130ec2a60cc0966622c9CVE reference · x_refsource_MISC
- https://github.com/withastro/astro/releases/tag/%40astrojs%2Fnode%409.5.4CVE reference · x_refsource_MISC
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.
Server-Side Request Forgery (SSRF)
Server-Side Request Forgery (SSRF) represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.