Use of Externally-Controlled Format String Affecting edk2-tools package, versions *


Severity

Recommended
low

Based on CentOS security rating.

Threat Intelligence

EPSS
0.41% (34th percentile)

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  • Snyk IDSNYK-CENTOS10-EDK2TOOLS-19264024
  • published26 Aug 2026
  • disclosed25 Aug 2026

Introduced: 25 Aug 2026

NewCVE-2026-63073  (opens in a new tab)
CWE-134  (opens in a new tab)

How to fix?

There is no fixed version for Centos:10 edk2-tools.

NVD Description

Note: Versions mentioned in the description apply only to the upstream edk2-tools package and not the edk2-tools package as distributed by Centos. See How to fix? for Centos:10 relevant fixed versions and status.

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 implementation is outside the OpenSSL FIPS module boundary.

CVSS Base Scores

version 3.1