CVE-2026-48126

HIGHNVD 8.28.2—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.2 under NVD CVSS v3. EPSS exploit probability: 0.3%, top 75% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Elevated
8.2
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 8.2Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Algernon is a small self-contained pure-Go web server. Prior to 1.17.8, when algernon is started with --domain (or --letsencrypt, which silently turns on --domain at engine/flags.go:372), the request handler resolves the served directory by joining the configured --dir with the value of the client-supplied Host header. The join is performed by filepath.Join with no validation, so a Host: .. header walks one level above the document root. Subsequent file resolution then exposes everything in that parent directory — arbitrary file read, full directory listing, and, if any .lua file is present, server-side Lua execution. This vulnerability is fixed in 1.17.8.

CVSS v3
8.2
EG Score
8.2(medium)
EG Risk
—
EPSS
25.9%
KEV
Not listed

Published

May 26, 2026

Last Modified

May 26, 2026

Advisory Details (1)

Auto-updated Jun 3, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

Host header path traversal in --domain mode reads files and runs Lua from parent dir · Advisory · xyproto/algernon · GitHub

https://github.com/xyproto/algernon/security/advisories/GHSA-jc3j-x6pg-4hmv

Vendor Advisories for CVE-2026-48126(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
Go(1)
PackageVulnerable rangeFixed inDependents
github.com/xyproto/algernon—1.17.8—

Weakness Classification(3)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 8× in last 7d / 31× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-22 14:08 UTCEPSS rescore
  2. 2026-07-21 15:24 UTCEPSS rescore
  3. 2026-07-20 17:08 UTCEPSS rescore
  4. 2026-07-19 14:31 UTCEPSS rescore
  5. 2026-07-19 06:22 UTCOSV refresh
  6. 2026-07-19 02:29 UTCEPSS rescore
  7. 2026-07-18 10:04 UTCEPSS rescore
  8. 2026-07-16 17:03 UTCEPSS rescore
  9. 2026-07-15 16:57 UTCEPSS rescore
  10. 2026-07-15 02:00 UTCEPSS rescore
  11. 2026-07-13 22:30 UTCEPSS rescore
  12. 2026-07-13 06:13 UTCEPSS rescore
  13. 2026-07-12 05:46 UTCEPSS rescore
  14. 2026-07-11 08:27 UTCEPSS rescore
  15. 2026-07-09 19:10 UTCEPSS rescore
  16. 2026-07-08 15:16 UTCEPSS rescore
  17. 2026-07-07 13:46 UTCEPSS rescore
  18. 2026-07-06 16:27 UTCEPSS rescore
  19. 2026-07-06 02:23 UTCEPSS rescore
  20. 2026-07-05 02:30 UTCEPSS rescore
  21. 2026-07-04 06:31 UTCEPSS rescore
  22. 2026-07-01 15:07 UTCEPSS rescore
  23. 2026-06-30 23:22 UTCEPSS rescore
  24. 2026-06-28 14:07 UTCEPSS rescore
  25. 2026-06-28 04:56 UTCEPSS rescore
Show 53 more
  1. 2026-06-28 04:56 UTCEPSS rescore
  2. 2026-06-27 03:08 UTCEPSS rescore
  3. 2026-06-25 13:49 UTCEPSS rescore
  4. 2026-06-24 14:05 UTCEPSS rescore
  5. 2026-06-23 21:33 UTCEPSS rescore
  6. 2026-06-23 21:33 UTCEPSS rescore
  7. 2026-06-22 14:25 UTCEPSS rescore
  8. 2026-06-22 14:25 UTCEPSS rescore
  9. 2026-06-21 14:56 UTCEPSS rescore
  10. 2026-06-21 14:56 UTCEPSS rescore
  11. 2026-06-21 01:59 UTCEPSS rescore
  12. 2026-06-21 01:59 UTCEPSS rescore
  13. 2026-06-19 19:26 UTCEPSS rescore
  14. 2026-06-19 19:26 UTCEPSS rescore
  15. 2026-06-18 17:52 UTCEPSS rescore
  16. 2026-06-18 17:52 UTCEPSS rescore
  17. 2026-06-17 17:53 UTCEPSS rescore
  18. 2026-06-16 17:53 UTCEPSS rescore
  19. 2026-06-15 17:49 UTCEPSS rescore
  20. 2026-06-15 17:49 UTCEPSS rescore
  21. 2026-06-14 23:18 UTCEPSS rescore
  22. 2026-06-13 23:00 UTCEPSS rescore
  23. 2026-06-12 23:12 UTCEPSS rescore
  24. 2026-06-12 23:12 UTCEPSS rescore
  25. 2026-06-11 14:00 UTCEPSS rescore
  26. 2026-06-10 22:18 UTCEPSS rescore
  27. 2026-06-10 13:22 UTCEPSS rescore
  28. 2026-06-10 13:22 UTCEPSS rescore
  29. 2026-06-08 14:17 UTCEPSS rescore
  30. 2026-06-08 14:17 UTCEPSS rescore
  31. 2026-06-07 15:25 UTCEPSS rescore
  32. 2026-06-07 15:25 UTCEPSS rescore
  33. 2026-06-06 13:47 UTCEPSS rescore
  34. 2026-06-06 13:47 UTCEPSS rescore
  35. 2026-06-05 22:47 UTCEPSS rescore
  36. 2026-06-05 06:10 UTCEPSS rescore
  37. 2026-06-05 06:10 UTCEPSS rescore
  38. 2026-06-04 13:12 UTCEPSS rescore
  39. 2026-06-04 13:12 UTCEPSS rescore
  40. 2026-06-02 20:13 UTCEPSS rescore
  41. 2026-06-01 13:52 UTCEPSS rescore
  42. 2026-06-01 13:52 UTCEPSS rescore
  43. 2026-05-31 22:30 UTCEPSS rescore
  44. 2026-05-31 22:30 UTCEPSS rescore
  45. 2026-05-31 00:16 UTCEPSS rescore
  46. 2026-05-31 00:16 UTCEPSS rescore
  47. 2026-05-29 13:44 UTCEPSS rescore
  48. 2026-05-29 13:44 UTCEPSS rescore
  49. 2026-05-28 13:44 UTCEPSS rescore
  50. 2026-05-28 13:44 UTCEPSS rescore
  51. 2026-05-27 13:40 UTCEPSS rescore
  52. 2026-05-27 13:40 UTCEPSS rescore
  53. 2026-05-26 17:02 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-48126?
CVE-2026-48126 is a high vulnerability published on May 26, 2026. Algernon is a small self-contained pure-Go web server. Prior to 1.17.8, when algernon is started with --domain (or --letsencrypt, which silently turns on --domain at engine/flags.go:372), the request handler resolves the served directory by joining the configured --dir with the value of the…
When was CVE-2026-48126 disclosed?
CVE-2026-48126 was first published in the National Vulnerability Database on May 26, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-48126 actively exploited?
CVE-2026-48126 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 25.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-48126?
CVE-2026-48126 has a CVSS v3 base score of 8.2 (NVD).
How do I remediate CVE-2026-48126?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-48126, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-48126

Explore →

Is Your Infrastructure Affected by CVE-2026-48126?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs