CVE-2026-71478

MEDIUMPre-NVD 6.16.1—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.1 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 90% 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, secondary
Elevated
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: Elevated riskExposed: 0

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

league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 1.5.0 until 2.9.0, the AttributesExtension's href and src unsafe-link filter can be bypassed by embedding control bytes, such as a tab, carriage return, line feed, or leading C0 control character, in a javascript: URL that browsers discard before parsing the scheme, causing the browser to still execute the script even when the unsafe-link filter is enabled. This issue is fixed in 2.9.0.

CVSS v3
6.1
EG Score
6.1(medium)
EG Risk
43(Track)
EG Risk 43/100SSVC: 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%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
10%
KEV
Not listed

Published

August 6, 2026

Last Modified

August 7, 2026

Advisory Details (3)

Auto-updated Aug 6, 2026
Patch available. Sources: github_commit, github_release, github.
github Patch Available

AttributesExtension href/src unsafe-link filter bypass via embedded control bytes · Advisory · thephpleague/commonmark · GitHub

Affected: v2.7.0 — that fix made

https://github.com/thephpleague/commonmark/security/advisories/GHSA-29pj-957v-52mc
github_release Patch Available

2.9.0

Patch available: thephpleague/commonmark 2.9.0

https://github.com/thephpleague/commonmark/releases/tag/2.9.0
github_commit Patch Available

commit 493a5aa7d657 (thephpleague/commonmark)

Patch available: thephpleague/commonmark 2.9.0 (contains commit 493a5aa7d657)

https://github.com/thephpleague/commonmark/commit/493a5aa7d65754b73846006eaff9c2c4431a8e2c

Vendor Advisories for CVE-2026-71478(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)
Packagist(1)
PackageVulnerable rangeFixed inDependents
league/commonmark1.5.0 ... 2.8.3 (65 versions)2.9.0—

Weakness Classification(3)

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

Data Freshness Timeline

(refreshed 15× in last 7d / 28× 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. 2026-08-20 22:56 UTCEPSS rescore
  2. 2026-08-19 21:58 UTCEG score recompute
  3. 2026-08-19 17:04 UTCEPSS rescore
  4. 2026-08-18 21:41 UTCEG score recompute
  5. 2026-08-18 13:49 UTCEPSS rescore
  6. 2026-08-18 13:49 UTCEPSS rescore
  7. 2026-08-17 21:20 UTCEG score recompute
  8. 2026-08-17 13:47 UTCEPSS rescore
  9. 2026-08-16 21:03 UTCEG score recompute
  10. 2026-08-16 14:56 UTCEPSS rescore
  11. 2026-08-16 14:56 UTCEPSS rescore
  12. 2026-08-16 02:15 UTCEPSS rescore
  13. 2026-08-15 20:46 UTCEG score recompute
  14. 2026-08-15 01:31 UTCEPSS rescore
  15. 2026-08-14 20:29 UTCEG score recompute
  16. 2026-08-13 22:00 UTCEPSS rescore
  17. 2026-08-12 19:53 UTCEG score recompute
  18. 2026-08-12 13:51 UTCEPSS rescore
  19. 2026-08-11 19:37 UTCEG score recompute
  20. 2026-08-11 00:00 UTCEPSS rescore
  21. 2026-08-09 19:00 UTCEG score recompute
  22. 2026-08-09 13:47 UTCEPSS rescore
  23. 2026-08-08 18:44 UTCEG score recompute
  24. 2026-08-08 16:37 UTCEPSS rescore
  25. 2026-08-07 18:27 UTCEG score recompute
Show 3 more
  1. 2026-08-07 17:27 UTCEG score recompute
  2. 2026-08-06 22:38 UTCEG score recompute
  3. 2026-08-06 21:07 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-71478?
CVE-2026-71478 is a medium vulnerability published on August 6, 2026. league/commonmark is a PHP library for parsing and rendering CommonMark Markdown. From 1.5.0 until 2.9.0, the AttributesExtension's href and src unsafe-link filter can be bypassed by embedding control bytes, such as a tab, carriage return, line feed, or leading C0 control character, in a…
When was CVE-2026-71478 disclosed?
CVE-2026-71478 was first published in the National Vulnerability Database on August 6, 2026, with the most recent update on August 7, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-71478 actively exploited?
CVE-2026-71478 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 89.7% of all scored CVEs.
What is the CVSS score of CVE-2026-71478?
CVE-2026-71478 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2026-71478?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-71478, 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

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