How should we interpret CVSS severity scores?

CVSS estimates technical severity, but it does not automatically equal business risk. Prioritize using context like internet exposure, asset criticality, known exploitation, and whether compensating controls exist. A Medium CVSS on an exposed production system can be more urgent than a Critical on an isolated non-production host.

Vulnerability Database

Q: What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

Q: What's the difference between a vulnerability, an exploit, and a zero-day?

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. Risk increases sharply when exploitation becomes reliable or widespread.

Q: Why do vulnerabilities keep reappearing in our environment?

Recurring findings usually come from incomplete asset discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host.

Q: How do we prioritize remediation without burning out the team?

Use a repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress so remediation is steady, not reactive.

Q: How can SynScan help reduce vulnerability risk over time?

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.

358,842

Total vulnerabilities in the database

PHP JWT Library: RSA1_5 (RSAES-PKCS1-v1_5) decryption lacks implicit rejection, exposing a Bleichenbacher/Marvin padding oracle — web-token / jwt-library

Observable Timing Discrepancy

Impact

RSACrypt::decryptWithRSA15() (used by the RSA1_5 key-encryption algorithm) implements RSAES-PKCS1-v1_5 decryption by inspecting the padding after RSADP and throwing InvalidArgumentException as soon as the padding is malformed. It does not implement the implicit-rejection countermeasure required by RFC 3447 §7.2.2 / RFC 8017 §7.1.2 (return a deterministic pseudo-random value of the expected length on padding failure and let the downstream step fail uniformly).

From a JWE caller this yields a Bleichenbacher/Marvin padding oracle: an attacker submitting adaptively crafted encrypted_key values can distinguish (a) padding rejected, (b) padding valid but wrong CEK length, and (c) padding valid and full AEAD executed — even though JWEDecrypter returns the same false in all cases — because each path performs a measurably different amount of work, amplifiable by enlarging the ciphertext (CWE-208 timing side channel). Enough adaptive queries can recover the wrapped CEK.

Affected configurations

Applications that register RSA1_5 in their decryption AlgorithmManager and hold an RSA private key.

Patches

PKCS#1 v1.5 decryption now performs implicit rejection: on invalid padding (or unexpected recovered length) it returns a random CEK of the expected size selected in constant time, so the full content-decryption (AEAD) step always runs and fails uniformly, removing the observable difference between padding-valid and padding-invalid ciphertexts. Users are still strongly encouraged to migrate to RSA-OAEP.

Workarounds

Prefer RSA-OAEP/RSA-OAEP-256; do not enable RSA1_5 for untrusted tokens.

References

RFC 3447 §7.2.2 / RFC 8017 §7.1.2
Bleichenbacher (1998); Marvin attack
CWE-208: Observable Timing Discrepancy

Résolution

Un correctif a été préparé sur une branche dédiée basée sur 3.4.x, avec des tests anti-régression dédiés (fork privé temporaire de cette advisory, PR #1).

RSA1_5 — déchiffrement PKCS#1 v1.5 avec implicit rejection en temps constant (RFC 3447 §7.2.2) : un padding invalide n'est plus distinguable d'un padding valide, neutralisant l'oracle Bleichenbacher.

Validation : php -l OK, PHPUnit vert, aucune nouvelle erreur PHPStan introduite (différentiel nul vs 3.4.x), aucun commentaire ajouté dans le code source. Après merge, cascade prévue 3.4.x → 4.0.x → 4.1.x.

Published: Jun 18, 2026
Updated: Jun 19, 2026
GHSA: GHSA-5739-39v2-5754
Severity: Medium
Exploit:
CISA KEV:

No technical information available.

CWEs:

Affected Software
References

Software	From	Fixed in
web-token / jwt-library	-	3.4.10
web-token / jwt-framework	-	4.1.6.x
web-token / jwt-library	4.0.0	4.0.7
web-token / jwt-library	4.1.0	4.1.7

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Frequently Asked Questions

What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.