CVE-2021-41106

MEDIUMNVD 4.44.4—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 4.4 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 89% 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
Trending — 3 sources updated this week
4.4
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 4.4Exploit: NoneExposed: 0

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

JWT is a library to work with JSON Web Token and JSON Web Signature. Prior to versions 3.4.6, 4.0.4, and 4.1.5, users of HMAC-based algorithms (HS256, HS384, and HS512) combined with Lcobucci\JWT\Signer\Key\LocalFileReference as key are having their tokens issued/validated using the file path as hashing key - instead of the contents. The HMAC hashing functions take any string as input and, since users can issue and validate tokens, users are lead to believe that everything works properly. Versions 3.4.6, 4.0.4, and 4.1.5 have been patched to always load the file contents, deprecated the Lcobucci\JWT\Signer\Key\LocalFileReference, and suggest Lcobucci\JWT\Signer\Key\InMemory as the alternative. As a workaround, use Lcobucci\JWT\Signer\Key\InMemory instead of Lcobucci\JWT\Signer\Key\LocalFileReference to create the instances of one's keys.

CVSS v3
4.4
EG Score
4.4(medium)
EG Risk
24(Track)
EG Risk 24/100SSVC: 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
Severity44% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
10.7%
KEV
Not listed

Published

September 28, 2021

Last Modified

November 18, 2025

References (6)

Affected Packages

(1 across 1 ecosystem)
Packagist(1)
PackageVulnerable rangeFixed inDependents
lcobucci/jwt4.1.0, 4.1.1, 4.1.2, 4.1.3, 4.1.44.1.5—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 51× 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.

Showing the most recent 100 of 104 total refreshes for this CVE.

  1. 2026-07-23 02:04 UTCEG score recompute
  2. 2026-07-22 22:50 UTCEG score recompute
  3. 2026-07-22 14:06 UTCEPSS rescore
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  75. 2026-05-26 09:49 UTCEG score recompute

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Frequently asked(5)

What is CVE-2021-41106?
CVE-2021-41106 is a medium vulnerability published on September 28, 2021. JWT is a library to work with JSON Web Token and JSON Web Signature. Prior to versions 3.4.6, 4.0.4, and 4.1.5, users of HMAC-based algorithms (HS256, HS384, and HS512) combined with Lcobucci\JWT\Signer\Key\LocalFileReference as key are having their tokens issued/validated using the file path as…
When was CVE-2021-41106 disclosed?
CVE-2021-41106 was first published in the National Vulnerability Database on September 28, 2021, with the most recent update on November 18, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-41106 actively exploited?
CVE-2021-41106 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 10.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-41106?
CVE-2021-41106 has a CVSS v3 base score of 4.4 (NVD).
How do I remediate CVE-2021-41106?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-41106, 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.

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