diff --git a/ChangeLog.d/issue4093.txt b/ChangeLog.d/issue4093.txt
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+Security
+   * Fix an errorneous estimation for an internal buffer in
+     mbedtls_pk_write_key_pem(). If MBEDTLS_MPI_MAX_SIZE is set to an odd
+     value the function might fail to write a private RSA keys of the largest
+     supported size.
+     Found by Daniel Otte, reported in #4093 and fixed in #4094,
+     backported in #4099.