GHSA-rm8v-mxj3-5rmq github.com/lestrrat-go/jwx vulnerable to Potential Padding Oracle Attack
The library leaks padding length via timing and error messages during AES-CBC decryption, potentially aiding padding oracle attacks.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is GHSA-rm8v-mxj3-5rmq?
GHSA-rm8v-mxj3-5rmq is a vulnerability in github.com/lestrrat-go/jwx, published on 14 Jun 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Summary
Decrypting AES-CBC encrypted JWE has Potential Padding Oracle Attack Vulnerability.
Details
On v2.0.10, decrypting AES-CBC encrypted JWE may return an error "failed to generate plaintext from decrypted blocks: invalid padding":
Reporting padding error causes Padding Oracle Attack Vulnerability. RFC 7516 JSON Web Encryption (JWE) says that we MUST NOT do this.
> 11.5. Timing Attacks > To mitigate the attacks described in RFC 3218 [RFC3218], the > recipient MUST NOT distinguish between format, padding, and length > errors of encrypted keys. It is strongly recommended, in the event > of receiving an improperly formatted key, that the recipient > substitute a randomly generated CEK and proceed to the next step, to > mitigate timing attacks.
In addition, the time to remove padding depends on the length of the padding. It may leak the length of the padding by Timing Attacks.
To mitigate Timing Attacks, it MUST be done in constant time.
Impact
The authentication tag is verified, so it is not an immediate attack.
Which versions are affected by GHSA-rm8v-mxj3-5rmq?
6 open source packages ship an affected version, including github.com/lestrrat-go/jwx and github.com/lestrrat-go/jwx/v2.
| Package | Affected | Fixed in |
|---|---|---|
github.com/lestrrat-go/jwx Go | All versions | 1.2.26 |
github.com/lestrrat-go/jwx Go | All versions | 1.2.26 |
github.com/lestrrat-go/jwx Go | All versions | 1.2.26 |
github.com/lestrrat-go/jwx/v2 Go | All versions | 2.0.11 |
github.com/lestrrat-go/jwx/v2 Go | All versions | 2.0.11 |
github.com/lestrrat-go/jwx/v2 Go | All versions | 2.0.11-0.20230614080639-c8b6bec919a1 |
How do I fix GHSA-rm8v-mxj3-5rmq?
Upgrade github.com/lestrrat-go/jwx to 1.2.26 or later.
Is GHSA-rm8v-mxj3-5rmq being exploited?
There is no known exploitation of GHSA-rm8v-mxj3-5rmq in the wild and no public exploit code.
Sources
Also known as GO-2023-1859.