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Padding Oracle Attack due to Observable Timing Discrepancy in jose-browser-runtime

Moderate severity GitHub Reviewed Published Apr 15, 2021 in panva/jose • Updated Mar 26, 2023

Package

npm jose-browser-runtime (npm)

Affected versions

< 3.11.4

Patched versions

3.11.4

Description

Impact

AES_CBC_HMAC_SHA2 Algorithm (A128CBC-HS256, A192CBC-HS384, A256CBC-HS512) decryption would always execute both HMAC tag verification and CBC decryption, if either failed JWEDecryptionFailed would be thrown. But a possibly observable difference in timing when padding error would occur while decrypting the ciphertext makes a padding oracle and an adversary might be able to make use of that oracle to decrypt data without knowing the decryption key by issuing on average 128*b calls to the padding oracle (where b is the number of bytes in the ciphertext block).

Patches

A patch was released which ensures the HMAC tag is verified before performing CBC decryption. The fixed versions are >=3.11.4.

Users should upgrade to ^3.11.4.

Credits

Thanks to Morgan Brown of Microsoft for bringing this up and Eva Sarafianou (@esarafianou) for helping to score this advisory.

References

@panva panva published to panva/jose Apr 15, 2021
Published by the National Vulnerability Database Apr 16, 2021
Reviewed Apr 16, 2021
Published to the GitHub Advisory Database Apr 19, 2021
Last updated Mar 26, 2023

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS score

0.149%
(52nd percentile)

Weaknesses

CVE ID

CVE-2021-29444

GHSA ID

GHSA-94hh-pjjg-rwmr

Source code

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