CVE-2026-31873

MEDIUMNVD 6.16.1—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.1 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 85% 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
6.1EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.1Exploit: None knownExposed: 0

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

Unhead is a document head and template manager. Prior to 2.1.11, The link.href check in makeTagSafe (safe.ts) uses String.includes(), which is case-sensitive. Browsers treat URI schemes case-insensitively. DATA:text/css,... is the same as data:text/css,... to the browser, but 'DATA:...'.includes('data:') returns false. An attacker can inject arbitrary CSS for UI redressing or data exfiltration via CSS attribute selectors with background-image callbacks. This vulnerability is fixed in 2.1.11.

CVSS v3
6.1
EG Score
6.1(medium)
EG Risk
32(Track)
EG Risk 32/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity61% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
15%
KEV
Not listed

Published

March 12, 2026

Last Modified

June 17, 2026

Advisory Details (1)

Auto-updated Aug 6, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

Bypass of URI Scheme Sanitization in makeTagSafe via Case-Sensitivity · Advisory · unjs/unhead · GitHub

https://github.com/unjs/unhead/security/advisories/GHSA-5339-hvwr-7582

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFixed inDependents
unhead—2.1.11—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 5× in last 7d / 29× 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. 2026-09-13 16:47 UTCEPSS rescore
  2. 2026-09-12 15:01 UTCEPSS rescore
  3. 2026-09-11 14:52 UTCEPSS rescore
  4. 2026-09-10 09:34 UTCEPSS rescore
  5. 2026-09-08 22:00 UTCEPSS rescore
  6. 2026-09-07 16:01 UTCEPSS rescore
  7. 2026-09-06 13:47 UTCEPSS rescore
  8. 2026-09-06 13:47 UTCEPSS rescore
  9. 2026-09-04 05:06 UTCEPSS rescore
  10. 2026-09-02 19:40 UTCOSV refresh
  11. 2026-09-02 14:11 UTCEPSS rescore
  12. 2026-09-01 13:53 UTCEPSS rescore
  13. 2026-09-01 04:39 UTCEPSS rescore
  14. 2026-09-01 04:39 UTCEPSS rescore
  15. 2026-08-30 19:17 UTCEPSS rescore
  16. 2026-08-30 01:22 UTCEPSS rescore
  17. 2026-08-28 21:41 UTCEPSS rescore
  18. 2026-08-27 14:25 UTCEPSS rescore
  19. 2026-08-26 14:46 UTCEPSS rescore
  20. 2026-08-25 13:49 UTCEPSS rescore
  21. 2026-08-24 14:17 UTCEPSS rescore
  22. 2026-08-21 23:49 UTCEPSS rescore
  23. 2026-08-20 22:55 UTCEPSS rescore
  24. 2026-08-20 22:55 UTCEPSS rescore
  25. 2026-08-19 17:03 UTCEPSS rescore
Show 27 more
  1. 2026-08-18 13:48 UTCEPSS rescore
  2. 2026-08-17 13:47 UTCEPSS rescore
  3. 2026-08-16 14:56 UTCEPSS rescore
  4. 2026-08-16 11:43 UTCEG score recompute
  5. 2026-08-16 02:14 UTCEPSS rescore
  6. 2026-08-15 01:30 UTCEPSS rescore
  7. 2026-08-12 22:45 UTCEG score recompute
  8. 2026-08-12 13:50 UTCEPSS rescore
  9. 2026-08-11 04:51 UTCEG score recompute
  10. 2026-08-11 00:00 UTCEPSS rescore
  11. 2026-08-10 05:19 UTCEG score recompute
  12. 2026-08-09 13:46 UTCEPSS rescore
  13. 2026-08-09 07:23 UTCEG score recompute
  14. 2026-08-08 16:37 UTCEPSS rescore
  15. 2026-08-07 18:05 UTCEG score recompute
  16. 2026-08-06 13:46 UTCEPSS rescore
  17. 2026-08-06 01:56 UTCEG score recompute
  18. 2026-08-05 19:17 UTCEPSS rescore
  19. 2026-08-04 15:10 UTCEPSS rescore
  20. 2026-08-04 10:38 UTCEPSS rescore
  21. 2026-08-02 17:21 UTCEG score recompute
  22. 2026-08-02 02:27 UTCEPSS rescore
  23. 2026-08-01 04:16 UTCEPSS rescore
  24. 2026-07-30 16:28 UTCEPSS rescore
  25. 2026-07-30 01:30 UTCEPSS rescore
  26. 2026-07-28 15:36 UTCEPSS rescore
  27. 2026-07-27 13:37 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-31873?
CVE-2026-31873 is a medium vulnerability published on March 12, 2026. Unhead is a document head and template manager. Prior to 2.1.11, The link.href check in makeTagSafe (safe.ts) uses String.includes(), which is case-sensitive. Browsers treat URI schemes case-insensitively. DATA:text/css,... is the same as data:text/css,... to the browser, but…
When was CVE-2026-31873 disclosed?
CVE-2026-31873 was first published in the National Vulnerability Database on March 12, 2026, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-31873 actively exploited?
CVE-2026-31873 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 85.2% of all scored CVEs.
What is the CVSS score of CVE-2026-31873?
CVE-2026-31873 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2026-31873?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-31873, 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-2026-31873

Explore →

Is Your Infrastructure Affected by CVE-2026-31873?

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

Start Free Scan →Browse All CVEs