Short answer: technically yes.

Yet doing this (Bahasa SMS) is not illegal.
There are a few laws in Malaysia where one can get into trouble with sexting:
- Sections 211 and 233 of the Communications and Multimedia Act 1998
- Section 292 of the Penal Code
- And if it is to/from/between under age parties, the Sexual Offences Against Children Act 2017 may potentially apply
Sections 211 and 233 of the Communications and Multimedia Act 1998
Sections 211 of the Communications and Multimedia Act 1998 reads as:
(1) No content applications service provider, or other person using a content applications service, shall provide content which is indecent, obscene, false, menacing, or offensive in character with intent to annoy, abuse, threaten or harass any person.
(2) A person who contravenes subsection (1) commits an offence and shall, on conviction, be liable to a fine not exceeding fifty thousand ringgit or to imprisonment for a term not exceeding one year or to both and shall also be liable to a further fine of one thousand ringgit for every day or part of a day during which the offence is continued after conviction.
Essentially anyone who uses a "content applications service" in an "indecent [and] obscene" manner commits an offence.
So if SMS is not a "content applications service"? Or OTT messaging services (like Whatsapp)?
Well, section 233 of the Communications and Multimedia Act 1998 would close that loop:
(1) A person who —
(a) by means of any network facilities or network service or applications service knowingly —
(i) makes, creates or solicits; and
(ii) initiates the transmission of,
any comment, request, suggestion or other communication which is obscene, indecent, false, menacing or offensive in character with intent to annoy, abuse, threaten or harass another person; or
(b) initiates a communication using any applications service, whether continuously, repeatedly or otherwise, during which communication may or may not ensue, with or without disclosing his identity and with intent to annoy, abuse, threaten or harass any person at any number or electronic address,
commits an offence.
(2) A person who knowingly —
(a) by means of a network service or applications service provides any obscene communication for commercial purposes to any person; or
(b) permits a network service or applications service under the person 's control to be used for an activity described in paragraph (a),
commits an offence.
(3) A person who commits an offence under this section shall, on conviction,be liable to a fine not exceeding fifty thousand ringgit or to imprisonment for a term not exceeding one year or to both and shall also be liable to a further fine of one thousand ringgit for every day during which the offence is continued after conviction.
Section 233 of the Communications and Multimedia Act 1998 has been interpreted VERY broadly, scooping up bloggers, Malaysia-Today, fan fiction. people who insult the Sultan of Perak, cartoonists, people who call the rules "fornicating", Zaid Ibrahim, "businessmen", forex traders, whatever the heck this was, insulting Johor royalty, mentally ill people, etc
Honestly it could be extended to sexting without too much imagination.
Section 292 of the Penal Code
Section 292 of the Penal Code deals with "obscenity". In part, it criminalises:
Whoever— (a) sells, lets to hire, distributes, publicly exhibits or in any manner puts into circulation, or for purposes of sale, hire, distribution, public exhibition or circulation makes, produces or has in his possession any obscene book, pamphlet, paper, drawing, painting, representation or figure or any other obscene object whatsoeverTry not to get too descriptive eh?
Section 11 of the Sexual Offences Against Children Act 2017
The section speaks for itself:
(1) Subject to subsection (3), any person who—
(a) sexually communicates with a child; or
(b) encourages a child to sexually communicate,
by any means, commits an offence and shall, on conviction, be punished with imprisonment for a term not exceeding three years
(2) For the purposes of this section, a person is said to sexually communicate if—
(a) the communication or any part of the communication relates to an activity that is sexual in nature; or
(b) any reasonable person would consider any part of the communication to be sexual.
Unlike the Penal Code, which defines a minor as 16 years of age, (but see the Child Act 2001, which defines a "child" as someone under 18), the Sexual Offences Against Children Act 2017 applies to anyone who is under 18.
So yes, technically sexting would run afoul of some Malaysian laws.