This page tracks the Ubuntu fix status. The vulnerability itself is described on the main CVE page. View CVE-2026-63073 →
Categories
UBUNTU-CVE-2026-63073

Issue summary: OpenSSL CMP response validation passed an unexpected response sender distinguished name directly as the format string to `ERR_raise_dat...

Original description

The description as published by the source.

Issue summary: OpenSSL CMP response validation passed an unexpected response sender distinguished name directly as the format string to ERR_raise_data(). Impact summary: A malicious or intercepted CMP endpoint can crash a CMP client that enforces an expected sender or uses a pinned server certificate whose subject becomes the default expected sender. CWE: CWE-134 (Use of Externally-Controlled Format String) Description: When validating a received CMP message, ossl_cmp_msg_check_update() converts the peer-supplied sender distinguished name with X509_NAME_oneline() and passes it directly as the format argument to ERR_raise_data(). Percent characters survive the conversion, so a sender DN such as "CN=%s%n" reaches BIO_vsnprintf() as an attacker-controlled format string with no matching variadic arguments. This path is only reached when the caller configures an expected sender or pins a server certificate, which is the normal configuration for a CMP client validating server responses. Since the attacker controls the format string but none of the variadic arguments, such specifiers as %s and %n dereference or write through unrelated stack contents and crash the client. The reliable consequence is a denial of service, when the response comes from a malicious or intercepted CMP endpoint. There is no controlled memory write, arbitrary-address read, or reliable path to remote code execution. FIPS impact: no No FIPS modules are affected by this issue, as the CMP protocol implementati…

Source: OSV.dev (Open Source Vulnerabilities) OSV

Affected packages

Ubuntu:Pro:16.04:LTS nodejs
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:18.04:LTS nodejs
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:26.10 edk2
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:26.10 edk2-hwe
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:26.04:LTS edk2
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:26.04:LTS edk2-hwe
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:26.04:LTS openssl
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.5.5-1ubuntu3.4"}]}]

References

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