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CVE-2020-8286 Moderate

Inferior OCSP verification

libcurl offers "OCSP stapling" via the `CURLOPT_SSL_VERIFYSTATUS` option. When set, libcurl verifies the OCSP response that a server responds with as part of the TLS handshake. It then aborts the TLS negotiation if something is wrong with the response. The same feature can be enabled with `--cert-status` using the curl tool. As part of the OCSP response verification, a client should verify that the response is indeed set out for the correct certificate. This step was not performed by libcurl when built or told to use OpenSSL as TLS backend. This flaw would allow an attacker, who perhaps could have breached a TLS server, to provide a fraudulent OCSP response that would appear fine, instead of the real one. Like if the original certificate actually has been revoked.

Exploit probability 4.6%
Published December 9, 2020
Required by Not available
Last source change May 27, 2026

02 / AFFECTED SOFTWARE

Affected packages

Unknown Unknown

50 explicit affected versions

Unknown Unknown

103 explicit affected versions

03 / CONNECTIONS

Connected vulnerabilities

04 / EVIDENCE

Source records

Open Source Vulnerabilities CVE-2020-8286

curl 7.41.0 through 7.73.0 is vulnerable to an improper check for certificate revocation due to insufficient verification of the OCSP response.

View original source
Open Source Vulnerabilities CURL-CVE-2020-8286

libcurl offers "OCSP stapling" via the `CURLOPT_SSL_VERIFYSTATUS` option. When set, libcurl verifies the OCSP response that a server responds with as part of the TLS handshake. It then aborts the TLS negotiation if something is wrong with the response. The same feature can be enabled with `--cert-status` using the curl tool. As part of the OCSP response verification, a client should verify that the response is indeed set out for the correct certificate. This step was not performed by libcurl when built or told to use OpenSSL as TLS backend. This flaw would allow an attacker, who perhaps could have breached a TLS server, to provide a fraudulent OCSP response that would appear fine, instead of the real one. Like if the original certificate actually has been revoked.

View original source

05 / REFERENCES

Further evidence