crypto/x509: ParseCRL allows CRL files to have duplicate revoked entries and duplicate certificate serial numbers.

[onepeople158]

Go version

go version go1.24.2 linux/amd64

Output of go env in your module/workspace:

CRL Issuer: CN=My Root CA,OU=My Root CA,O=My Company,L=San Francisco,ST=California,C=US
This Update Time: 2025-01-01 08:00:00 +0800 CST
Next Update Time: 2025-12-01 08:00:00 +0800 CST
Signature Algorithm: SHA256-RSA
Number of Revoked Certificates: 3

Revoked Entry Details:
============================
Serial Number: 1c80022ef81f2405ee96a612dcb61fe0ac701e5e
Revocation Time: 2025-04-17 18:16:51 +0800 CST
  (No extensions)
----------------------------
Serial Number: 8cb8193ecce671ec00000000582c8a7a
Revocation Time: 2025-04-14 20:00:00 +0800 CST
  Extensions:
    2.5.29.21 (CRL Reason): CessationOfOperation
----------------------------
Serial Number: 8cb8193ecce671ec00000000582c8a7a
Revocation Time: 2025-03-14 20:00:00 +0800 CST
  Extensions:
    2.5.29.21 (CRL Reason): KeyCompromise

CRL Issuer: CN=My Root CA,OU=My Root CA,O=My Company,L=San Francisco,ST=California,C=US
This Update Time: 2025-01-01 08:00:00 +0800 CST
Next Update Time: 2025-12-01 08:00:00 +0800 CST
Signature Algorithm: SHA256-RSA
Number of Revoked Certificates: 2

Revoked Entry Details:
============================
Serial Number: 8cb8193ecce671ec00000000582c8a7a
Revocation Time: 2025-04-14 20:00:00 +0800 CST
  Extensions:
    2.5.29.21 (CRL Reason): CessationOfOperation
----------------------------
Serial Number: 8cb8193ecce671ec00000000582c8a7a
Revocation Time: 2025-04-14 20:00:00 +0800 CST
  Extensions:
    2.5.29.21 (CRL Reason): CessationOfOperation
----------------------------

What did you do?

Hello developer, I successfully parsed a CRL file with duplicate revoked certificate entries or duplicate serial numbers using go. According to RFC 5280:

Each revocation entry is uniquely identified by its serial number.

What did you see happen?

I successfully parsed a CRL file with duplicate revoked certificate entries or duplicate serial numbers using go.

What did you expect to see?

crl_revoked_dublicate.zip
crl_revoked_dublicate_serial.zip

Code:

go.zip

[gabyhelp]

Related Issues

• crypto/x509: ParseCRL allows revocation serial number that is a non-positive integer #73433
• affected/package: x509 CreateRevocationList incorrect serial? #53923 (closed)
• crypto/x509: ParseRevocationList accepts two AKI extensions #73051
• crypto/x509: the ParseRevocationList() doesn't seem to populate the AuthorityKeyId correctly #57461 (closed)
• crypto/x509: ParseCRL allows the Invalidity Date of revoked certificates in the CRL to be UTC time #73442
• crypto/x509: ParseCertificate and ParseCertificateRequest should return an error when there are duplicate x509 extensions #50988 (closed)
• crypto/x509: RevocationList.CheckSignatureFrom doesn't check Subject #60728
• crypto/x509: ParseRevocationList incorrect handling of the CRL Number field #73029
• crypto/x509: CRL generated by Certificate.CreateCRL is still version 1 #13931 (closed)

Related Code Changes

• crypto/x509: reject CRL revoked certs w/ negative serial

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[JunyangShao]

@rolandshoemaker

[AGWA]

FYI, here is an argument that duplicate serial numbers in CRLs is not actually forbidden by RFC 5280 (I neither endorse nor reject this argument): https://bugzilla.mozilla.org/show_bug.cgi?id=1943379#c7

Here's the CABF issue to update the BRs to explicitly forbid it: cabforum/servercert#589

[onepeople158]

FYI, here is an argument that duplicate serial numbers in CRLs is not actually forbidden by RFC 5280 (I neither endorse nor reject this argument): https://bugzilla.mozilla.org/show_bug.cgi?id=1943379#c7

Here's the CABF issue to update the BRs to explicitly forbid it: cabforum/servercert#589

Thank you for sharing the detailed analysis and ongoing discussions regarding the interpretation of RFC 5280 and the proposed updates to the CAB Forum Baseline Requirements (BRs).