CVE-2021-29443 [Medium] | Security Vulnerability in Jose

jose is an npm library providing a number of cryptographic operations. In vulnerable versions 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. 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). All major release versions have had a patch released which ensures the HMAC tag is verified before performing CBC decryption. The fixed versions are `^1.28.1 || ^2.0.5 || >=3.11.4`. Users should upgrade their v1.x dependency to ^1.28.1, their v2.x dependency to ^2.0.5, and their v3.x dependency to ^3.11.4. Thanks to Jason from Microsoft Vulnerability Research (MSVR) for bringing this up and Eva Sarafianou (@esarafianou) for helping to score this advisory.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2025-03-30	0.61%	0.32%	-0.30%
2	2025-03-29	0.32%	0.61%	+0.30%
3	2025-03-17	—	0.32%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2025-03-30

0.61%

0.32%

-0.30%

2025-03-29

0.32%

0.61%

+0.30%

2025-03-17

—

0.32%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.9	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:N) Service keeps running; no real outage angle.	2.2	3.6	[email protected]
5.9	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:N) Service keeps running; no real outage angle.	2.2	3.6	[email protected]
4.3	2.0	MEDIUM	`AV:N/AC:M/Au:N/C:P/I:N/A:N` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:M) Exploitation needs some favorable conditions, but not exceptional ones. Authentication (AU:N) No authentication is required. Confidentiality impact (C:P) Partial confidentiality impact. Integrity impact (I:N) No integrity impact. Availability impact (A:N) No availability impact.	8.6	2.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

5.9

3.1

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:N): Service keeps running; no real outage angle.

2.2

3.6

[email protected]

5.9

3.1

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:N): Service keeps running; no real outage angle.

2.2

3.6

[email protected]

4.3

2.0

MEDIUM

AV:N/AC:M/Au:N/C:P/I:N/A:N Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:M): Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:P): Partial confidentiality impact.
Integrity impact (I:N): No integrity impact.
Availability impact (A:N): No availability impact.

8.6

2.9

[email protected]

Affected software / configurations for CVE-2021-29443

Vendor	Product	Version	Raw CPE
jose_project	jose	>= 1.0.0, < 1.28.1	cpe:2.3:a:jose_project:jose::::::node.js::*
jose_project	jose	>= 2.0.0, < 2.0.5	cpe:2.3:a:jose_project:jose::::::node.js::*
jose_project	jose	>= 3.0.0, < 3.11.4	cpe:2.3:a:jose_project:jose::::::node.js::*

References for CVE-2021-29443

URL	Tags
https://github.com/panva/jose/security/advisories/GHSA-58f5-hfqc-jgch	Patch Third Party Advisory
https://www.npmjs.com/package/jose	Third Party Advisory

URL

CVE-2021-29443 | Padding Oracle Attack due to Observable Timing Discrepancy in jose

Exploit prediction scoring system (EPSS) score for CVE-2021-29443

Common vulnerability scoring system (CVSS) metrics for CVE-2021-29443

Weakness enumeration for CVE-2021-29443

GitHub Security Advisory for CVE-2021-29443

Affected software / configurations for CVE-2021-29443

References for CVE-2021-29443